Rav was a descendant of a distinguished Babylonian family which claimed to trace its origin to Shimei, brother of King David. His father, Aibo, was a brother of Hiyya the Great who lived in Palestine, and was a highly esteemed scholar in the collegiate circle of the patriarch Judah haNasi. From his associations in the house of his uncle, and later as his uncle's disciple and as a member of the academy at Sepphoris, Rav acquired such knowledge of the tradition as to make him its foremost exponent in Babylonia. While Judah haNasi was still living, Rav, having been ordained as teacher (with certain restrictions), returned to Babylonia, where he at once began a career that was destined to mark an epoch in the development of Babylonian Judaism.