Shi'a sources say they were Jews,[9] But a Jewish source says that they and the Banu Khazraj were Arab tribes from Yemen who came to Medina in the fourth century. The Jewish source says that the two tribes took the power of Medina from the Jews in the 5th century by "calling in outside assistance and treacherously massacring at a banquet".[3] However, all sources agree that the Banu Aus and the Banu Khazraj became hostile to each other.