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Nova Season 53 Episode 2
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00:13An iconic temple.
00:15The largest religious monument in the world.
00:18Angkor Wat is an enduring enigma.
00:21The engineering feat of Angkor Wat is unbelievable.
00:25In the heart of one of the greatest ancient cities ever built, Angkor.
00:29One of the largest, if not the largest city in the world at the time.
00:33Home to over 1,000 temples.
00:36Each new king would try to outbuild the rain before
00:39and build a bigger and more impressive temple.
00:42But then the temples and the city were engulfed by the jungle.
00:46It mysteriously was abandoned.
00:50Or so the story goes.
00:52There are few clues.
00:55Almost every wooden remain and the vast majority of structures at Angkor were built in wood
01:01deteriorate very, very quickly.
01:04And many mysteries.
01:06The lack of bodies.
01:08One million people, not a bone, not a cremated remain.
01:13It was fascinating and frustrating.
01:16There's another story there sitting underneath.
01:18Now, archaeologists are using the latest technologies to reveal Angkor's hidden secrets.
01:24Sarah took the LiDAR data.
01:26She used some machine learning algorithms.
01:28To see through the jungle.
01:29The LiDAR data is absolutely mind-blowing.
01:32It was all into the landscape.
01:34And look into the past.
01:36I really like the pages of a history book.
01:38To find new evidence of a great civilization.
01:41They didn't just build Angkor Wat, which is a spectacular temple, right?
01:44Like, they were transforming the entire landscape.
01:47Angkor, Hidden Jungle Empire.
01:50Right now on NOVA.
02:02In the jungles of Cambodia, a spectacular ruin rises from the trees.
02:17This is Angkor Wat.
02:21A 900-year-old temple filled with intricate carvings and mysterious figures.
02:28It is the largest religious monument in the world.
02:32And a masterpiece of ancient engineering.
02:35The engineering feat of Angkor Wat is unbelievable.
02:40It's amazing.
02:42Angkor Wat is the centerpiece of the ancient city of Angkor.
02:48A marvel of vast infrastructure.
02:51Built with a network of human-made canals and enormous reservoirs.
02:56Angkor was the heart of a wealthy and dynamic empire that thrived for 600 years.
03:03Then around 1300, suddenly the buildings stopped.
03:07This vast, ornate city was largely abandoned.
03:11Why?
03:13Archaeologists like Pip-Al-Hang are trying to answer that question.
03:17And to understand the people of Angkor.
03:20Monumental architecture like Angkor Wat has been its signature.
03:24When you talk about Angkor, it's monument.
03:27Part of my archaeological endeavor is to understand Angkorians people's life.
03:34What did they do?
03:35What was the relationship between the people and the city?
03:38The relationship between the people and the temple?
03:41And how did that change through time?
03:44The ancient city of Angkor was one of the biggest pre-industrial cities in the world.
03:58Located in Cambodia in Southeast Asia, its legendary temple, Angkor Wat, is its most iconic structure.
04:06But Angkor Wat is the largest of more than a thousand temples spread across more than 150 square miles.
04:19A lot of these temples have really been left to the jungle.
04:21So trees are overgrowing them, the vegetation is everywhere.
04:24And when you walk into them, you sometimes feel like you're the first person that stepped foot in them for over a thousand years.
04:32The temples themselves have a sense of mystery to them.
04:35You don't know exactly what happened here or why they were abandoned.
04:38This land has been home to the Khmer people for thousands of years, living in small kingdoms often in conflict with each other.
04:48Until the year 802, when Jayavarman II defeated his rivals and declared himself a god-king in the Hindu tradition and founded the Khmer Empire.
05:03Nearly 100 years later, the capital of the empire was moved to a new site on a fertile plain, the city of Angkor.
05:14Over the next 500 years, the empire became the dominant power in Southeast Asia, ruling over all of what is now Cambodia and much of Vietnam, Thailand and Laos.
05:27The kings, who were considered holy, ruled both political and spiritual life.
05:32Each successive ruler strove to demonstrate his greatness through major construction projects.
05:38Each new king and each new reign would try to outbuild the reign before and build a bigger and more impressive temple.
05:45As Angkor grew, so did the temples, in number and size.
05:52Until the 1300s, when temple construction abruptly stopped.
05:57Evidence suggests that by the mid-1400s, Angkor stood empty.
06:04It mysteriously was abandoned.
06:14Or so the story goes.
06:16And so this place has attracted the fascination of people from around the world for many, many hundreds of years.
06:23Partly because the city itself is so prodigiously massive.
06:28And partly because all of this was apparently left to the jungle by the Khmer.
06:34The abandonment of Angkor is an enduring mystery.
06:38Who were the people who lived here?
06:40And why did they leave?
06:42The answers are important, not just for the archaeologists who were excavating here.
06:52Many Cambodians identify as Khmer and are deeply invested in this ancient place.
06:58Angkor is central to their heritage, connecting them to their ancestors.
07:04Angkor holds a profound place in Khmer life.
07:09The very word Angkor is deeply rooted in our national identity.
07:15Angkor, we can say for the Khmer people, it's our soul.
07:19Every one of the Khmer people say that we want to see Angkor before we die.
07:24But the full truth about Angkor and its people has been elusive.
07:29Because so much of the city has long lain hidden beneath the jungle canopy.
07:34We only know of Angkor what this one square kilometer temple as being a religious temple, a sacred space.
07:43But were there any people living inside Angkor? We did not know yet.
07:48We also tried to map the area and the vegetation was too thick. It was overgrown.
07:54It's incredibly difficult for archaeologists to map the center of Angkor where all the large temples are because of all the dense vegetation.
08:01But now, with the help of new technology, archaeologists are trying to see what has been invisible for centuries.
08:09That's where the LiDAR data comes in.
08:12LiDAR is a powerful laser technology that has recently become a game changer for archaeologists.
08:18LiDAR has been absolutely revolutionary for our field of archaeology because it allows us to see the ground floor underneath dense vegetation.
08:27We acquire LiDAR data by putting a drone or a helicopter or plane in the air with the LiDAR device on it.
08:33These devices send out millions of pulses of light.
08:36Most of those pulses bounce off things that we're not interested in like buildings or trees.
08:41But some of them critically reach the ground surface.
08:44What we do is we measure the time that it takes for those ground returns to return to the LiDAR device.
08:50And using those measurements, calculate distance.
08:54With that information, we can then strip away all the vegetation so we can clearly see these archaeological features.
09:01The LiDAR scans revealed the breathtaking size of the city.
09:07The data was spectacular.
09:09All of a sudden, we could see these elements of the urban space that were completely invisible before.
09:15The LiDAR data is like the most amazing treasure map, not because we're looking for gold or statues,
09:20but because it allows us to ask bigger and better questions about what it was like to live at Angkor.
09:26The amount of detail that the LiDAR revealed about the landscape is absolutely mind-blowing.
09:31We were able to map an additional 20,000 features.
09:35The full scale of the city of Angkor is staggering, covering more than 150 square miles about the size of Denver.
09:46Hundreds of miles of roads and a complex network of waterways and canals connected the city.
09:53Hidden in the data were the keys to knowing how and where the citizens of Angkor lived.
10:01Because Angkor is built on a floodplain, all of the features were built on mounds.
10:06So when we're looking at the LiDAR data, we're not seeing ancient houses themselves,
10:10but we're seeing the mounds these houses were once built on.
10:14This is Angkor Wat, which is absolutely beautiful in the LiDAR data.
10:21So these are depressions and elevations in the land that we can very clearly see in this LiDAR imagery,
10:27but it's almost impossible to see these features on the ground because the vegetation is just so dense.
10:33All of these black dots are house ponds and beside them are usually house mounds.
10:39Within the Angkor Wat temple enclosure itself, the LiDAR revealed more than 200 of these mounds.
10:46Using the LiDAR maps as a guide, Pipple Hang set out to investigate these sites on the ground.
10:53Those mounds are generally habitation sites.
10:56When we saw a similar pattern inside the Angkor Wat enclosure, we started to excavate those mounds.
11:04Turned out that those mounds have residential trees, ceramics,
11:10Angkorian stonewares, and trade ware from China.
11:14So what we didn't know was those mounds and ponds were arranged into a grid system.
11:19That's when LiDAR came around.
11:25So here we are in the eastern section of the Angkor Wat enclosure.
11:29What I am standing on now would have been a house mount.
11:33And because of the overgrown, we can hardly tell the topographic change,
11:38but LiDAR map allowed us to pick up just a slight topographic change
11:42that allowed us to identify whether this area was mount upon to my right.
11:48The LiDAR data shows that we are standing in an urban block
11:53that is replicated into other urban blocks covering the entire Angkor Wat enclosure.
12:00You can tell when you're walking around that there's mounds there.
12:03It's really forested, but you can see that the landscape undulates quite a bit.
12:08Archaeologist Allison Carter has been collaborating with Papal
12:12to try to decipher what life was like at the Angkor Wat complex.
12:16The LiDAR in Angkor was incredibly eye-opening because you just see that
12:22they didn't just build Angkor Wat, which is a spectacular temple, right?
12:25Like they were transforming the entire landscape.
12:28And transforming it with extreme precision.
12:31If you look at the temple structures and align them with the gates of Angkor Wat,
12:37you would see that the grid system was actually aligned with the temple.
12:43It was all an engineered landscape.
12:45The remarkable urban design of the Khmer extended to the even larger royal complex, Angkor Thom.
12:54You can see this is Angkor Wat.
12:56There's a huge moat that's very visible from the satellite imagery.
12:59And then up here is Angkor Thom.
13:02You can see the moat of Angkor Thom.
13:04But you really can't see all of that detail that becomes so clear and obvious in the LiDAR data.
13:10So you can just imagine when you enter Angkor Thom through these magnificent gates,
13:17it would have been a bustling city on either side of you.
13:20Again and again, the LiDAR revealed sprawling neighborhoods around Angkor's more than 1,000 temples.
13:27Combining this with the finds from excavations on the ground and new technologies,
13:33a team of archaeologists is finally able to crack one of the city's biggest mysteries.
13:39The size of Angkor's population at its peak around 1250.
13:44To answer that question of how many people lived at Angkor,
13:47we compiled all of the data that we had.
13:49C-14 dates, ceramic evidence from excavation,
13:52and we used some new cutting edge algorithms and machine learning techniques to try to model the development of the city over time.
14:00I was part of a group of people that were working on trying to understand the growth of the city of Angkor.
14:07If we compare, this one is better.
14:09That one's better. It's a much bigger piece, yeah.
14:11So that'll be great to collect from this mound.
14:14That's a really good example of how we can bring in good old-fashioned on-the-ground dirt archaeology
14:19with all of these new technologies.
14:21From our excavations, it seems like there's just one household or family per mound.
14:25We use ethnographic data then to estimate that there's about five people in a family.
14:30Another important piece of data was from inscriptions.
14:33A lot of the temples have foundation dates,
14:35and that was really important to understand when they were built.
14:39And inscriptions in two of the larger temples provide crucial clues about the population,
14:45which are of special interest to archaeologist Andrew Harris.
14:49They actually list the numbers of temple staff.
14:53These include government officials, dancers, laborers,
14:57and also how many people that the temple staff oversaw in the surrounding villages,
15:04numbering between 200,000 and 300,000 for both temples.
15:08And then Sarah took that data, the LiDAR data.
15:11She used some machine learning algorithms.
15:13We brought this all together to try and create a model for how Angkor grew.
15:17The final estimate from their calculations was staggering.
15:21From our estimates, we think at its height that it had about 700,000 to 900,000 people
15:25living in the greater Angkor region.
15:27That would have made it one of the largest, if not the largest, city in the world at the time.
15:32The discovery of Angkor's true size was a major breakthrough.
15:37But it was all the more impressive because of Angkor's location.
15:41Because the entire city was built on a water-soaked floodplain.
15:46Every year, the rainy season brings massive rainfall and heavy flooding.
15:52My family's connection with Angkor runs deep.
15:57During my childhood, my grandparents and my parents frequent the pagoda in Angkor,
16:05so I've been coming to Angkor since forever.
16:09Growing up here provides a different perspective on the water.
16:13We have the Great Lake to the south.
16:16The lake level changed drastically during the rainy season, particularly around October and November.
16:23The Great Tonle Sap Lake often quadruples in size in the rainy season, flooding vast areas of the countryside.
16:31In the dry season, nearly half the year, almost no rain falls.
16:36Why would the Khmer build in a place with such extreme swings between flooding and droughts?
16:42Water is incredibly important for the Khmer empire. Almost everything revolves around it.
16:48And one of the most important functions was irrigating the main agricultural crop of the empire, rice.
16:56The economy of Angkor was underpinned by rice agriculture, which is heavily dependent on a stable supply of water.
17:02There's a strong relationship between water, the floodplain, wet rice agriculture, and the early phase of Angkor period.
17:11As the Khmer empire and city expanded, controlling the flow of water was key for their economy, trade, and ability to feed a growing population.
17:21But how did they do it?
17:23Visible remnants suggested there had once been a complex water system.
17:28But it took LIDAR to reveal the full scope of the Khmer engineering.
17:33So with the LIDAR we were able to create this map, which very clearly shows the layout of the water management system,
17:40and how water flows into the city, through the city, and then how there are exit channels to remove excess water.
17:46The design was both ambitious and ingenious. A series of massive reservoirs called barai's collected water in the rainy season.
17:55So here at Angkor, we can see the large barai's. Here's the west and east barai.
18:00And then all of these straight lines funneling into the city, these are man-made water channels.
18:06So this is rerouting water from northern areas of Cambodia into Angkor.
18:13The water was captured from natural rivers and moved into storage in these massive reservoirs.
18:20Those barai's were really the centerpiece of the whole system.
18:23The largest barai stretched across more than six square miles.
18:28All of these features are so big that you can literally see them from space.
18:33That's the beginning of Angkor's power of water management.
18:40Those reservoirs are fantastically important.
18:43They hold huge volumes of water, which can be distributed in the dry season.
18:46If you want a second crop of rice, for example.
18:49So it really kind of super boosts your productivity in those parts of Angkor, which are downstream of those reservoirs.
18:55And the system extended far beyond the city itself.
18:59The landscape around Angkor is actually at a slight incline, about 1%.
19:05So the east and west barai can catch water as it comes into the city, hold it, and then redistribute it through the different channels.
19:14Taming the water was a major feat of urban engineering, with hundreds of miles of canals and reservoirs all dug by hand.
19:24But the floodplain also created a major challenge for an empire intent on creating monumental architecture.
19:32It's a bit of a difficult spot for building heavy temples like Angkor.
19:37So in order to do this, they had some really ingenious engineering strategies.
19:42How did the Khmer manage to build massive stone structures on soft, deep soil surrounded by water?
19:49The first clue may be in the choice of building material.
19:54Hang Pao is the head of Apsara, the organization in charge of restoring the city of Angkor and the surrounding area.
20:03The priority of Apsara is about the conservation.
20:07How we can preserve the temple without falling.
20:12Before we start to make the restoration, we need to do research.
20:17The highly decorated walls of Angkor's temples are built of fine-grained sandstone, well-suited for intricate carvings.
20:27But appearances can be deceiving.
20:30Just under the ornate facade lies the first secret of Khmer construction.
20:36Hidden within the walls and foundation are blocks of a rough, porous stone called laterite that can be even lighter than sandstone.
20:47In terms of the web, it's less heavy.
20:51The core inside, they build in the laterite.
20:54And then they put the lampstone around for decoration.
20:59The whole temple is built in that concept.
21:03Using the lighter laterite greatly reduced the load on the soft ground.
21:08But the stone temples are still incredibly heavy.
21:12The stone that forms Angkor Wat, towering over 200 feet high, weighs millions of tons.
21:20And yet, it has survived the wet terrain for over 900 years.
21:25There must be more to the engineering.
21:28But what?
21:30Archaeologist Net Simone leads restoration teams for Apsara.
21:37Her excavations are focused on understanding the key elements of ancient Khmer engineering.
21:43As a result of the excavation to see the condition of the foundation, I was able to understand the ancient techniques in building the temple.
21:55We observed that before shaping the temple itself, the ancient builders began by digging down to reach the natural soil.
22:04They then began compacting the soil inside.
22:10The next step involved filling the foundation with fine pink sand.
22:15This was followed by the laterite foundation.
22:19Above it, they laid the base layer using sandstone.
22:23As any trip to the beach reveals, dry sand is soft and shifts easily, while wet sand, closer to the water, holds firm.
22:34Water and sand together can create a solid base for construction.
22:39This could be one reason the temples at Angkor were surrounded by moats.
22:44Another thing that we can see is that all of these temples have water features around them.
22:48So each temple, which is marked in red, they tend to have moats around them.
22:54They build on the sand layer.
22:57And we understand that the sand layers need a lot of the humidity to make it stronger to support the load of the temple.
23:06The moats were, and still are, key to maintaining the required level of moisture beneath the biggest buildings.
23:12The water in the moats provide stability to the sand, which allows them to hold the heavy, heavy stone structures up.
23:19These innovations demonstrate that the Khmer were masters of hydraulic engineering.
23:27As do the hidden features that enabled Angkor's massive reservoirs, the burais, to function.
23:34Cambodian archaeologist, An Sopit, and his team are excavating a unique location on the edge of the eastern burais,
23:44an ancient reservoir long dry and now covered in jungle.
23:49Right in front of me is the East Burais, a water reservoir from the Angkor era.
23:57These are the ruins of an ornate stone pier overlooking the burais.
24:03The Cambodian government hopes to restore the pier and partially repair the reservoir to make it functional once more.
24:11The first step is to understand how both were constructed.
24:17But while excavating the pier and the reservoir wall, they found an unexpected surprise.
24:23At the excavation site I opened here, we found the foundation of the pier, made from laterite rock.
24:33Hidden beneath the wall of the burais is a laterite stone foundation extending more than 50 feet out into the reservoir.
24:42This work is important because it reveals a new discovery.
24:47We had never seen a construction with laterite sloping like this before.
24:53The next step is to determine if this massive foundation extends along the banks of the reservoir, beyond the area of the pier.
25:01We opened another excavation site 10 meters to the south and saw the structure continues with four more steps.
25:12But we only exposed a small section to confirm.
25:15In the future, we'll keep excavating to see if the laterite structure surrounds the water reservoir or ends somewhere.
25:22No one knows yet how far this stone foundation extends around the barai.
25:30If this structure goes around a reservoir or part of it, it would be a new discovery for the Angkor area.
25:38The pier itself was a very special structure for Angkor's Hindu god kings.
25:43This pier was used by the king to offer alms at the temple located at the center of the eastern reservoir.
25:53In the middle of each reservoir was an island temple.
25:58The burais were more than just a brilliant piece of hydraulic engineering.
26:02Here's the east burai and you can clearly see both in the mapping and in the lidar data that there's a huge temple in the middle of it.
26:09These large reservoirs were both functional and spiritual.
26:14The kings of the Khmer Empire played both a political and a religious role.
26:18In addition to being head of the army, the king was also a king god, so head of the religious system as well.
26:24Every king left an imprint of himself if he was powerful enough to create a mark on the landscape.
26:30Dozens of temples here are reflective of the absolute power over nature, over people, and over the landscape that they manifested during their reign.
26:44Over the centuries, rulers built larger and larger temples as the Khmer Empire expanded.
26:50Early in his reign in the 1100s, King Suryavarman II outdid all his predecessors, building Angkor Wat.
27:01Angkor Wat was a huge project. It would involve so many workers and so many craftsmen to be able to build it.
27:07Dedicated to the Hindu god Vishnu, nearly every surface of Angkor Wat was highly decorated.
27:15Traces of paint found on the carved walls and ceilings hint at its ornate history.
27:20All of the reliefs on the temples were originally painted in vibrant colors.
27:26Immense carved panels with scenes from Hindu texts run down vast hallways.
27:33Thousands of priests, dancers, and attendants filled the temple and its grounds.
27:40It was a ceremonial center on a grand scale, demonstrating the glory of Vishnu and the power of the king.
27:50Temples were not just places of worship. The kings were also using them to demonstrate their power,
27:56so they probably were really acting as this kind of billboard for the king and the king's power and putting his stamp on the landscape.
28:03Wealthy and prosperous, the Khmer Empire was an attractive target for neighboring powers.
28:10Carved scenes at Angkor illustrate the story of one major conflict.
28:15In 1177, the nearby kingdom of Cham invaded Angkor in a surprise attack.
28:25To reclaim the city and restore power to the empire would take one of the strongest of the Khmer kings, Jayavarman VII.
28:33In the year 1177, the Chams conquered Angkor and occupied Angkor.
28:40Jayavarman VII made it his vow to reconquer Angkor.
28:45And part of this is depicted through various campaigns of warfare.
28:49This is probably the most elaborate of those campaigns and it involves a naval battle.
28:55What we can tell here is that one, it was intensive, it was violent.
29:00You could see the people falling overboard. Most of them have been stabbed or dead or whatnot.
29:05And a lovely crocodile eating a poor Cham who's fallen overboard.
29:08So through a series of campaigns lasting several years, he was able to eventually vanquish the Chams.
29:19With the enemy defeated and the Khmer back in power, Jayavarman VII would usher in Angkor's golden age.
29:27During his reign, he gave back to the public in many ways.
29:29He constructed hospitals and he built a number of different temples.
29:32This is a scene of a hospital. Here you have women giving birth, making medicine.
29:39This was a major point during the reign of Jayavarman VII.
29:43He built, I believe, 102 hospitals across the Angkorian Empire.
29:49Alongside his support of public health, Jayavarman carried on the tradition of his Khmer predecessors.
29:56Monumental construction.
29:58When kings came into power, they all had specific mandates that they had to accomplish.
30:02And a lot of this revolved around temple building.
30:05Angkorian kings had an undocumented habit of trying to one-up their predecessors.
30:12If you think about Suryavarman II, he built the world's largest religious monument, Angkor Wat.
30:18Jayavarman VII left the largest architectural footprint on the Angkorian landscape of any monarch in Cambodian history.
30:25The pinnacle of his reign was the construction of Angkor Thom, an enormous complex more than five times the size of Angkor Wat.
30:35It is surrounded by eight miles of moat, and at its center stands a temple different from any built before, or after.
30:44The Bayan.
30:48The Bayan is not a Hindu temple.
30:51Jayavarman was a Buddhist.
30:54All of the elite temples, up until the reign of Jayavarman VII, were considered to be Hindu temples of various deities.
31:00One of the most interesting things about King Jayavarman VII is that he switched the state religion from Hinduism to Buddhism.
31:08Hindu worship involves a pantheon of gods and observation of rituals set out in the Vedic scriptures,
31:15while Buddhism focuses on enlightenment through the teachings of the Buddha.
31:19The Bayan temple towers feature 216 enigmatic faces that may contain a hidden secret.
31:29The faces on the Bayan and the gate are potentially a Buddhist saint, or they're the king himself.
31:35And the reason we think it's Jayavarman VII himself is because a number of the images that we know of Jayavarman VII look almost identical to the face towers on the Bayan and on the gates.
31:47Following the reign of Jayavarman VII, ending around 1218, Angkor was at the height of its size and influence.
31:56What was life in Angkor like at its peak?
31:59Few written descriptions have survived from the Khmer, but historians have one detailed account.
32:05In the 13th century, the Emperor of China sent an emissary to Angkor.
32:09Joe de Guan was an ambassador of Mongolian-controlled China to Cambodia.
32:17He lived in Angkor sometimes between 1296 and 1297, almost one year.
32:23Joe de Guan left a journal, and it's incredibly valuable in terms of the types of details that he wrote about.
32:28I'm not sure if he intended for archaeologists to read this, but it sure provides a lot of information.
32:35Around the outside of the city walls, there is a large moat.
32:39The walls of the bridges are made of stone and carved into the shape of snakes.
32:43As an archaeologist, I refer to Joe de Guan constantly.
32:47He talks about how poor people lived in smaller houses and their roofs were made out of thatch,
32:52but richer people would have bigger houses and their roofs would be made with ceramic roof tiles.
32:58Joe de Guan's journal described scenes of everyday life.
33:02Their litters are made of pieces of wood that bend in the middle.
33:07A person sits in the cloth and is carried by two people, one at each end.
33:13The parasols are made of a strong, thin, red Chinese silk.
33:18But how reliable are Joe de Guan's descriptions?
33:23His descriptions of daily life are actually backed up by a lot of what we see on the walls of the Bion Temple.
33:30Joe de Guan describes Angkor as a bartering system and he describes a market day.
33:38He describes how merchants, mostly women, would lay down their blankets and sell their wares.
33:46The local people who know how to trade are all women.
33:50Small market transactions are paid for in rice or other grain and Chinese goods.
33:56Larger in size are paid with cloth.
33:59There's these bas-reliefs of people cooking and eating food and then in our archaeological excavations we find really similar materials.
34:07When we are excavating an occupation area and you're like, oh, this looks just like what's on the Bion,
34:14you can really see how these different sources of evidence come together to give you a more complete picture of the past.
34:19That record represents a fantastic contribution to our understanding of the life of the city.
34:24And at that time, the king and the court were very impressive.
34:27The city was enormous and there was clearly a lot of wealth floating around.
34:31Above the gates are stone Buddha heads.
34:33One of them is decorated with gold.
34:37In the center of the capital is a gold tower.
34:40Joe de Guan describes Angkor as a very active, very vibrant metropolis.
34:46He talks about the significant amount of wealth coming out of the palace.
34:50So Joe de Guan described the temples at Angkor not as these stone mounds that they are today, but covered in gold and very clearly upkept.
35:01But that upkeep would not last much longer.
35:05Joe de Guan's record represents the very kind of last gasp of Angkor as a spectacular, opulent, thriving metropolis.
35:14From that point forward, things change dramatically.
35:17This inscription indicates that this temple was the very last Hindu temple that was dedicated at Angkor.
35:32We actually have an exact date for it.
35:34It's the 28th of April, 1295 CE, which was just a year before Joe de Guan showed up.
35:42As far as we know, there are no temples after this one.
35:45As the 1300s continue, Angkor starts to decline.
35:50We start to see evidence from different sources that population starts to slide, there are no more inscriptions created, no more temples built.
36:00Official written histories of the Khmer did not appear again until much later.
36:06There's a bit of a black hole in the historical records from about the 13th century to the 15th century.
36:12So it's a big gap. It's many hundreds of years.
36:17What happened to bring an end to centuries of prosperity and monumental construction?
36:22No big city like this one is ever going to have a single reason for its start or its end.
36:27So in that context and in the complexity of that story, we can start to accept that there's no linear, simple, single explanation for the demise of a place like this, but rather a tangle of different explanations that happened to Kowal-Ess at a particular point.
36:40The warm and humid environment of the Cambodian jungle works against the archaeologists trying to shed light on the declining years of Angkor.
36:49The rainforest does not help because almost every wooden remain and the vast majority of structures at Angkor were built in wood deteriorate very, very quickly.
37:03One of the most puzzling aspects of Angkor today is the complete absence of human remains.
37:09No bodies, no burials.
37:12This is a very fascinating thing that's baffled archaeologists for a long time.
37:16There are no funerary remains until much later.
37:21So for 600 years, one million people, not a bone, not a cremated remain, not a funerary jar, not a trace of a funerary remain.
37:32The lack of bodies, human remains in Angkor's archaeological record is fascinating and frustrating in many ways.
37:45It's very rare for a city which had 700,000 million people in it that there are so few bodies.
37:52What happened to the bodies of the ancient Khmer?
37:55Well, Joe Daquan, he talks about different burial practices.
37:58The body is taken to a remote, uninhabited spot where it is thrown down and left.
38:06After that, the vultures, crows and dogs come and eat it.
38:12But the archaeologists at Angkor are struggling to find the location of the sky burials that Joe Daquan described,
38:20where the dead are left to the elements and animals.
38:22He said that they carried the dead outside of the Uncle Tom Gates and then left it outside the wall.
38:29But when we look at LiDAR data, outside the wall would have been just settlements everywhere.
38:34Where was that outside the wall?
38:37Burials do tell us a lot about health and the individuals.
38:41So to find a graveyard, or even to find cremated burials, that would be phenomenal for our colon archaeology.
38:49But so far we have not found evidence of a burial ground yet.
38:53Without the bodies themselves, archaeologists are searching for other clues, hoping to find out, when did everyone leave?
39:05Dan Penny is focusing on the burials and canals, and the sediments below the surface.
39:12The sediment is accumulating at the bottom of these reservoirs, ponds and so on.
39:19They end up as beautiful little traps for material, landing on the surface and then settling onto the sediment.
39:25And then being buried by subsequent layers of material.
39:29And so it goes, layer upon layer.
39:31We can come along hundreds, thousands of years later and take these samples and find this undisturbed material,
39:36which faithfully records the conditions that were occurring when they were deposited.
39:42The moats of Angkor Twom are a fantastic archive.
39:45They've been largely left alone, so we can use them as natural archives of change through time.
39:55This core goes all the way back to a pre-Angkor.
39:59So it goes into the alluvial soil beneath the moat,
40:02and we get the whole sequence all the way through the rise and fall of Angkor and into the modern day.
40:08After processing, Dan studies the samples from the sediment layers under a powerful microscope.
40:15So this guy here is a pollen grain from a lotus.
40:19This one is a sedge, so it's another aquatic plant.
40:22It's a huge chunk of charcoal coming out of maybe a domestic fire,
40:26someone's fireplace where they're cooking.
40:27It could be any source, but it's invariably associated with people.
40:30Radiocarbon dating adds another layer of information.
40:35Most of the work that I do with radiocarbon is actually based on dating the pollen grains themselves.
40:40Each of these pollen grains is about 10 to 20 micrometers in diameter.
40:46A micrometer is a thousandth of a millimeter, so they're pretty small.
40:50The types of pollen grains, found at different depths in the core,
40:55can reveal when the ancient moats were well maintained or filled with weeds.
41:00When moats are being maintained, you'll often see species rooted into the sediment at the bottom of the moat,
41:05as opposed to an unmaintained moat which is kind of completely covered by ferns and grasses and other things.
41:11Once management stops, the moats will quickly cover with vegetation.
41:16We definitely find evidence of the water systems not being maintained.
41:21Once they're abandoned, they are permanently abandoned,
41:24and so that represents a very clear horizon for us to say,
41:27hey, at this point this water feature is no longer being managed.
41:29What we are finding increasingly from a range of different variables, charcoal among them,
41:35pointing to a progressive decrease in the intensity of occupation in the very epicentre of Angkor as a city,
41:42all of these things are decreasing progressively through the 1300s.
41:47What could have happened at Angkor in the mid-1300s that would have caused the Khmer to leave?
41:54And the reality is that we don't really know what happened.
41:56There are a number of different hypotheses, and probably it was a combination of all of them.
42:01So we need to cast our mind to what other reasons might there have been for people to start leaving Angkor.
42:06There's another story there, sitting underneath, which is far more interesting and far more important.
42:11Angkor was not the only place to suffer a major population decrease during the 1300s.
42:18The Bubonic Plague, also known as the Black Death, that killed millions in Europe,
42:23came out of Asia during this century.
42:27The timing fits the abandonment of Angkor.
42:30But is there any evidence of a connection?
42:33Evidence of a pandemic at Angkor would be revolutionary.
42:37The effect of a pandemic in a pre-industrial city like this one, which was massive and had a huge population, would have been catastrophic.
42:47And it would likely have led to very rapid depopulation, particularly by those people that can move.
42:52If there's evidence of a pandemic, I can assure you there will not be.
42:59Because if you have a pandemic here, you will find bodies, right?
43:05Because there are 900,000 people here at the peak.
43:09If you have the plague here, it would have been horrific.
43:12And there would be no way that people would have been able to deal with that much human remains in the normal way.
43:21If it wasn't a cataclysmic event, could a slow decline have been triggered from within the Khmer Empire itself?
43:29What changed for the Khmer?
43:32A discovery during the restoration of Angkor's Tha Pram temple may provide a clue.
43:43Tha Pram was constructed as a Buddhist temple in honor of King Jayavarman, the seventh's late mother.
43:54The first step taken by her team was to conduct an initial survey.
43:59Our team discovered broken pieces of a Buddha statue.
44:06Once our team began digging and cleaning, more and more of the statue began to emerge from the ground.
44:14More than 140 pieces in total.
44:18Some of these sculptures were buried, while others were left scattered around the temple grounds.
44:24That's not when you don't.
44:28Tha Pram was not the only temple to see this kind of destruction.
44:33So we're at Priya Khan temple here.
44:36It was dedicated in the year 1191 to Jayavarman VII's father.
44:40What's on the left here is a series of niches where the Buddhas have been completely hacked out.
44:44And we think that this was an act of religious violence.
44:49What would have caused the Khmer to turn against Buddhism?
44:52We believe that in the 13th century, one of Jayavarman VII's successors, Jayavarman VIII, was responsible for this.
44:59And shifted the royal cult from Mahayana Buddhism back to Hinduism.
45:02This act was either due to religious reasons or even political reasons as a retaliation against the reign of Jayavarman VII.
45:11After Jayavarman VII's golden era under Mahayana Buddhism and Jayavarman VIII's Hindu backlash,
45:19the Khmer religion changed one last time to an older form of Buddhism called Theravada Buddhism.
45:26The Khmer Empire was undergoing another major cultural and religious shift.
45:33King Indravarman III essentially switched the entire religious ideology and landscape to Theravada Buddhism beginning during his reign in the year 1296.
45:45Chinese Ambassador Zhou de Guan arrived at Angkor just as the Empire moved to worshipping at Theravada Buddhist temples called Viharas.
45:56Zhou de Guan saw this society that was in transition and changing.
46:02Rather than more temples being constructed, it was now Vihara and monasteries.
46:06There were still construction activities after 1295.
46:10The type of structures, the type of temples changed because of Theravada Buddhism.
46:17The Theravada Buddhism only required a terrace surrounded by boundary stones and Buddha statues and then wooden structures.
46:27So that's very simple and that's what could drive a lot of change.
46:32The age of giant ornate stone temples was over.
46:35The shift away from huge temples and elaborate ceremony not only meant less construction, but fewer monks, dancers and religious staff.
46:46All this could have contributed to a shrinking population at Angkor in the 1300s.
46:52But would it have caused the Khmer to completely abandon such a vibrant city?
46:57Or was there another fatal blow to Angkor?
47:02We don't obviously have a historical record of climate from Angkor.
47:06There was nobody here recording it at the time.
47:09So what we have to do is look for other sources of information that can tell us that.
47:13We exploited some tree ring records from the mountains of Vietnam that tell us about rainfall in particular.
47:19And they tell us a really interesting story about variations in weather and climate during the period where Angkor is abandoned.
47:28The study showed a series of droughts at a time when Angkor was vulnerable.
47:33So those two droughts occurred from about the middle of the 14th century, from about 1350 onwards, and they lasted for about two decades more or less at a time.
47:45So they were really, really severe, quite profound, nothing like we have seen in the modern era.
47:50Angkor had survived droughts before, but this time may have been different.
47:55So you have the sense that Angkor is very successful, but it's building itself into a state of precariousness.
48:02So by the time it gets to the middle of the 1300s and you're hit with a massive drought and then a big wet period and another massive drought, the whole system starts to crack and come apart.
48:11Fractured it, shattered it by eroding, by sedimenting or infilling canals, blowing up banks and reservoirs, doing all sorts of damage to the system.
48:21You need to have the people who continue to have that knowledge. Without those people, everything collapsed.
48:29The LiDAR data also reveals some failures in the water management system.
48:33So here we can see where a channel cut through an embankment.
48:37You can see that this is going right through the middle of a densely occupied urban space.
48:42So this would have been devastating for the people that were living here at the time.
48:46And one of the other things is we can see that this failure was never repaired.
48:49At some point in the 1400s, the city of Angkor was largely abandoned.
48:56Only a handful of farmers, monks and religious pilgrims remained.
49:01Over time, the jungle covered the ancient heart of the Khmer Empire.
49:07For over 600 years, the seasonal floods and droughts ravaged the ancient monuments.
49:13Today, Cambodians have an ambitious plan. Restore the ancient hydraulic systems and bring the water back to Angkor and the surrounding area.
49:22Our ancient ancestors already designed and built working water systems.
49:32So as the younger generation, our work is simply to restore and rehabilitate.
49:38We are combining the use of ancient technology that already exists with our modern technology.
49:44Restoring the channels into the burais to prevent flooding and hold water has been successful.
49:55The northern burais is now full.
49:59So is the west burais, holding more than 13 billion gallons of water.
50:07The project to widen the canals and fill the ancient moats continues.
50:12Including work on the moat around Angkor Wat.
50:23In the same time, that system allows us to save the water for the dry season.
50:29It's impossible to have this level today if those systems are not put in place.
50:35Even in the end of the dry season, you will have nearly the same water level in Angkor Wat mode.
50:44Angkor's legacy reaches beyond Cambodia.
50:48Angkor is a location. It's also a representation of a culture and a civilization.
50:55The ways in which humans can flourish in difficult environments.
51:00It represents a celebration of the past and it represents a warning to our future.
51:04But for the Cambodian people, the centuries of history at Angkor form a central part of their identity.
51:13Through the transition from the Angkorian to the post-Angkorian period, it's social transformation.
51:20After the collapse of Angkor, it became a symbol of power.
51:25For the Khmer people, Angkor is an important cultural symbol.
51:32A reflection of the Khmer identity and soul.
51:38All the local people want to pay the respect to Angkor.
51:44Angkor, for the Cambodian people, it's a lot. Everything.
51:50The sacred aspect of Angkor, I never left Angkor. It's still here.
51:59It's still here today.
52:03It's still here today.
52:04It's still here today.
52:05It's still here today.
52:10Thank you very much.
52:12I amItalienan is a place and journey.
52:14And I am so excited.
52:17I am so excited in the world.
52:20It's a long way of walking through this story and I am a woman.
52:22It's still there.
52:23And I am so excited for you.
52:26Interesting, so few women are excited for me.
52:28The dichoteness also has become a type of space.
52:30It's still here today.
52:32Baby wings wererative, just as home.
52:34For Fvenant lifestyle of the creation.
52:36Transcription by CastingWords
53:06CastingWords
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