Pirqoy ben Baboy is known only as the author of a fairly short polemical treatise (Heb. iggeret, epistle), much of which has been preserved in a number of fragmentary manuscripts discovered in the Cairo Geniza, while other portions appear to be irretrievably lost. Pirqoy introduces himself at the beginning of this work as “the student of Rava, and Rava [was] the student of Rav Yehuday Gaon,” so that his floruit was approximately two generations later than that of the famous gaon Yehuday ben Naḥman, who died in 760 according to the Epistle of Sherira Gaon. We may therefore assume that Pir…