After Anan's death the Karaite community conferred the leadership on his son, Saul. Anan's disciples, who called themselves Ananites, differed on various points with their master, especially with regard to the prescribed mode of killing birds. Thus, immediately after Anan's death, the enduring character which he had desired to impart to religious life was destroyed, and there arose divisions which increased with every generation. This schism caused the Karaites to study the Bible more closely, and to support and strengthen their position against one another, and against the Rabbanites, from Holy Writ. It was for this reason that the study of the Bible was carried on by the Karaites with great ardor. With this study went hand in hand the knowledge of Hebrew grammar and of the Massora, the determination of the manner of reading the Holy Scripture. There sprang up many commentators on the Bible, and altogether a luxuriant literature was produced, as each party, thinking it had discovered something new in the Bible, desired to have its authority generally acknowledged.
While the Karaites thus were extremely active, the Rabbanites were most unfruitful in literary productions. A single work is all that is known to have appeared in those times. Judah, the blind Gaon of Sora, who has already been mentioned, and who had done much to oppose Anan's claim, composed a Talmudical Compendium, under the title "Short and Established Practice" (Halachoth Ketuoth). In this work Judah collected and arranged, in an orderly manner, the subjects which were scattered through the Talmud, and indicated briefly, omitting all discussions, what still held good in practice. To judge from a few fragments, Judah's Halachoth were written in Hebrew, by which means he rendered the Talmud popular and intelligible. For this reason the work penetrated to the most distant Jewish communities, and became the model for later compositions of a similar description.
The Karaite disturbances also contributed to lessen the authority of the Exilarch. Until the time of Anan the academies and their colleges had been subordinate to the Prince of the Captivity, and to the principals of the schools chosen or confirmed by him; at the same time, however, they had no direct influence over the appointment to this office when it became vacant. But having once succeeded in dispossessing Anan of the Exilarchate, the Gaons determined that this power should not be wrested from their hands, and accordingly from this time exercised it on the ground that they could not allow princes of Karaite opinions to be at the head of the Jewish commonwealth. The Exilarchate, which had been hereditary since the time of Bostanaï, became elective after Anan, and the presidents of the academies directed the election. On the death of Chananya (Achunaï), and hardly ten years after Anan's defection from Rabbanism, a struggle for the Exilarchate broke out afresh between two pretenders, Zaccaï ben Achunaï and Natronaï ben Chabibaï. The latter was a member of the college under Judah. The two heads of the schools at this period, Malka bar Acha, of Pumbeditha (771–773), and Chaninaï Kahana ben Huna, of Sora (765–775), united to bring about the overthrow of Natronaï, and succeeded in procuring, through the Caliph's attendants, his banishment from Babylonia. He emigrated to Maghreb (Kairuan), in which city there had existed ever since its foundation a numerous Jewish population. Zaccaï was confirmed in the office of Exilarch. The Exilarchate continued to become more and more dependent on the Gaonate, which often deposed obnoxious princes, and not infrequently banished them. But as the Exilarchs, when they arrived at power, attempted to free themselves from this state of dependence, there occurred collisions which exerted an evil influence on the Babylonian commonwealth.
At about the same time as Karaism sprang into existence, an event occurred which only slightly affected the development of Jewish history, but which roused the spirits of the scattered race and restored their courage. The heathen king of a barbarian people, living in the north, together with all his court, adopted the Jewish religion. The Chazars, or Khozars, a nation of Finnish origin, related to the Bulgars, Avars, Ugurs or Hungarians, had settled, after the dissolution of the empire of the Huns, on the frontier between Europe and Asia. They had founded a kingdom on the Volga (which they called the Itil or Atel) at the place near which it runs into the Caspian Sea, in the neighborhood of Astrakhan, now the home of the Kalmucks. Their kings, who bore the title of Chakan or Chagan, had led these warlike sons of the steppe from victory to victory. The Chazars inspired the Persians with so great a dread that Chosroes, one of their kings, found no other way of protecting his dominions against their violent invasions than by building a strong wall which blocked up the passes between the Caucasus and the sea. But this "gate of gates" (Bab al abwab, near Derbend) did not long serve as a barrier against the warlike courage of the Chazars. After the fall of the Persian empire, they crossed the Caucasus, invaded Armenia, and conquered the Crimean peninsula, which bore the name Chazaria for some time. The Byzantine emperors trembled at the name of the Chazars, flattered them, and paid them a tribute, in order to restrain their lust after the booty of Constantinople. The Bulgarians, and other tribes, were the vassals of the Chazars, and the people of Kiev (Russians) on the Dnieper were obliged to pay them as an annual tax a sword and a fine skin for every household. With the Arabs, whose near neighbors they gradually became, they carried on terrible wars.
Like their neighbors, the Bulgarians and the Russians, the Chazars professed a coarse religion, which was combined with sensuality and lewdness. The Chazars became acquainted with Islam and Christianity through the Arabs and Greeks, who came to the capital, Balanyiar, on matters of business, in order to exchange the products of their countries for fine furs. There were also Jews in the land of the Chazars; they were some of the fugitives that had escaped (723) from the mania for conversion which possessed the Byzantine Emperor Leo. It was through these Greek Jews that the Chazars became acquainted with Judaism. As interpreters or merchants, physicians or counselors, the Jews were known and beloved by the Chazar court, and they inspired the warlike king Bulan with a love of Judaism.
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.
It is possible that the circumstances under which the Chazars embraced Judaism have been embellished by legend, but the fact itself is too definitely proved on all sides to allow any doubt as to its reality. Besides Bulan, the nobles of his kingdom, numbering nearly four thousand, adopted the Jewish religion. Little by little it made its way among the people, so that most of the inhabitants of the towns of the Chazar kingdom were Jews; the army, however, was composed of Mahometan mercenaries. At first the Judaism of the Chazars must have been rather superficial, and could have had but little influence on their mind and manners. A successor of Bulan, who bore the Hebrew name of Obadiah, was the first to make serious efforts to further the Jewish religion. He invited Jewish sages to settle in his dominions, rewarded them royally, founded synagogues and schools, caused instruction to be given to himself and his people in the Bible