The "Hazar Peace" had accelerated the communication, increased the goods exchange, which made the khanate to a country where merchants and artists from Eastern and Western nations united in huge groups. Thus, various writings (Gok-Turk, Arabic, Hebrew, Kryllic) had been used beneath different languages. The inhabitants were of different religions. Actually the Hazar's believed in the Sky God ("Tengri-Han"), which had been the ancient Turkish-Steppe religion, based on the faith of unity of God.
Due to the close relations of the nations, all religions like Islam, Christian, Jewish was spread out over the country and each community carried out their own worships and ceremonies within total religious freedom. According to sources (Istahri, in 932, el-Mes'u-di, in 944, ibn Havkal, in 977) in the city of Hazar mosques, churches, synagogues were side by side. Although, it can be seen that the islamic religion (in the middle of the 9th century) was spread out by the Harezm, the Orthodox Christianity came from Byzantium (last quartar of 8th century) and had increased with the visit of Kryll (Kyrillos), the famous Islavic "apostol" to the capital Itil (861-862) upon the wish of the Hazar khane, it is not very clear when and how the Jewish religion had been accepted, especially as the only religion of the khan, his family and the administrating group. In general it is accepted that khane Bulan had be the one who made the Hazar turn to the Jewish religion, for which several dates are given. Latest examinations put forward that Bulan had changed religion in 8th century in Khersones (North Crimea).
According to some Islamic writers (el-Mes'udi), the Hazar's had entered a sect of the Jewish religion in the time of Harun'ur-Resid (786-809), the Abbasian chalif. This sect, that was called "Karay", did not pay much respect to "Talmud" of which it is believed to contain the teachings of Moses, and possibly had been a conviction mixed with some Islamic elements. It is said that the Hazar's because of this got closer to Talmudism in very short time. The letter that the Jewish minister Hasday b. Shaprut of the Andalusian Emevi state had sent from Kurtuba to the Hazar khan Yasef and the responding letter of the khane, of which it is said to be written in Hebrew, also did not lighten up the matter.
The content of the "correspondence" ("Correspondence Kha-zre"), which was found in Egypt in 16th century and published in Istanbul (1577) had been subject to scientific publications and statements (the best, P.P. Ko-kovtsov, 1932, Leningrad). Although criticism of the document had brought up serious doubts concerning the reality of the document, the rightness of the information that was given in the content could be proved in many ways. As a result it can be seen that members of the Karay religion (Karaims) got more and more crowded in the Hazar country and that the Karaims who are living in our time in Crimea, Lehistan and Turkey (Istanbul), at least the communities with the mother language and their religious language being Turkish, are even grandsons of the Jewish Hazar Turks and partly maybe of the Karaim Kumans.