Bostanai is the first exilarch under Arabian rule; he flourishes about the middle of the seventh century.
The name is Aramaized from the Persian "bustan" or "bostan".
Almost the only exilarch of whom anything more than the name is known, he is frequently made the subject of legends.
Bostanai is the son of the exilarch Hananiah.
Hai Gaon, in "Sha'are Ẓedeḳ," seems to identify Bostanai with Haninai, and tells that he was given for wife a daughter of the Persian king Khosrau II by the calif Umar.
Abraham ibn Daud, however, in his "Sefer ha-Ḳabbalah", says that it was the last Sassanid king, Yazdegerd, who gave his daughter to Bostanai.
But in that case it could have been only Caliph Ali, and not Umar, who thus honored the exilarch.
It is known also that Ali gave a friendly reception to the contemporary Gaon Isaac; and it is highly probable, therefore, that he honored the exilarch in certain ways as the official representative of the Jews.
The office of the exilarch, with its duties and privileges, as it existed for some centuries under the Arabian rule, may be considered to begin with Bostanai.
