An Exilarch
In late antiquity, the exilarch was the leader of the Jewish communities in Mesopotamia. During the Sasanian period, the office was held by members of a family that traced its ancestry back to the line of King David and functioned like the catholicos, the head of the Christian communities. In the early medieval period, the exilarch (Aramaic, resh galuta; Hebrew, rosh ha-golah; Arabic, ra’s al-jālūt) was still nominally the successor to the Davidic dynasty and head of the entire diaspora, but in practice, his authority was limited. By the ninth or tenth century, the exilarchs were living in Baghdad. Documents from the Cairo Geniza indicate that the position of exilarch existed until the thirteenth century and possibly up until the turn of the fifteenth, although its authority continued to diminish over time.