Largely based on the original Greek writings of Josephus, Sefer Yosippon is a historical narrative in Hebrew, written in southern Italy in the tenth century. The text is of anonymous authorship and describes the period of the Second Temple. It was popular in the Middle Ages. Several distinct translations into Judaeo-Arabic exist, by whose intermediation Sefer Yosippon was subsequently adopted by the Coptic Church. The Copto-Arabic recension, known as Kitab al-akhbār al-ʿibrāniyyin ‘The book of historical reports on the Hebrews’, not only gained an almost canonical in the Coptic Church, but also constituted a source for Muslim authors to acquaint themselves with Ancient Jewish history. Despite its importance, the Arabic versions –both of Jewish and Christian provenance - have remained largely unresearched and neglected by scholars. The proposed research therefore attempts a comprehensive study of Arabic versions of the Sefer Yosippon and its transmission history among the Coptic Church and Muslim authors.