In subsequent times, however, the Chazars had but a vague knowledge of the motive which induced their forefathers to embrace Judaism. One of their later Chagans gives the following account of their conversion: The king Bulan conceived a horror of the foul idolatry of his ancestors, and prohibited its exercise within his dominions, without, however, adopting any other form of religion. He was encouraged by a dream in his endeavors to discover the proper manner of worshiping God. Having gained a great victory over the Arabs, and conquered the Armenian fortress of Ardebil, Bulan determined to adopt the Jewish religion openly. The Caliph and the Byzantine emperor desired, however, to induce the king of the Chazars to embrace their respective religions, and with this intention sent to Bulan deputations with letters and valuable presents, and men well versed in religious matters. The king thereupon arranged for a religious discussion to take place before him between a Byzantine ecclesiastic, a Mahometan sage, and a learned Jew. The champions of the three religions disputed the whole question, however, without being able to convince one another or the king of the superior excellence of their respective religions as compared with the other two. But as Bulan had remarked that the representatives of the religion of Christ and of Islam both referred to Judaism as the foundation and point of departure of their faiths, he declared to the ambassadors of the Caliph and the Emperor that, as he had heard from the opponents of Judaism themselves an impartial avowal of the excellence of that religion, he would carry out his intention of professing Judaism as his religion. He thereupon immediately offered himself for circumcision. The Jewish sage who was the means of obtaining Bulan's conversion is supposed to have been Isaac Sanjari or Sinjari.