The great Turkic empire that held the northern Caucasus through the seventh and eighth centuries was in the business of choosing. The Khazar khagan controlled the passes between the Pontic steppe and the settled world to the south, extracted tribute from Slavic tribes to the north, defeated Arab armies pushing up through the Caucasus, and traded with Byzantines and Persians alike. He was a pragmatist on a grand scale. When it came to religion, he looked at what his powerful neighbours were selling and made a calculation. Byzantium offered Christianity; the Caliphate offered Islam. The Khazar khagan, according to his own letters and to a Hebrew correspondence that survives to this day, chose neither. He chose the Torah instead.
The story of that choice - debated, embellished, and celebrated across many centuries - centres on a disputation. Competing accounts, including the famous Kuzari dialogue written by the Spanish-Jewish poet and philosopher Yehudah Halevi in the twelfth century, describe the khagan summoning representatives of the three Abrahamic faiths and listening to each argue its case. The Christian and Muslim scholars, in the dialogue's telling, each independently concede that of the three, Judaism is the root from which their faiths grew. The khagan draws the logical conclusion. Whether or not a formal disputation ever occurred, what the historical record preserves is something more remarkable than a legend: a document in the khagan's own voice.
The record
The Khazar Correspondence - a collection of Hebrew letters exchanged in the tenth century between the Khazar king Joseph and the Andalusian Jewish statesman Hasdai ibn Shaprut - is the closest thing to a primary source the conversion story possesses. King Joseph's letter, in its longer recension preserved in manuscripts now held at the Russian National Library in St Petersburg (Firkovich collection) and studied in detail by the scholar Paul Kokovtsov in his 1932 edition Evreisko-khazarskaya perepiska, names a Khazar king called Bulan as the figure who led the conversion. Joseph places Bulan three generations before his own ancestor Obadiah, who later consolidated and deepened Jewish observance across the kingdom. Bulan's conversion is set loosely in the mid-eighth century - historians generally date it to around 740 CE, during the reign of the Khazar khagan who held the Caucasus passes against the Arab armies of the late Umayyad Caliphate.
What makes the Khazar conversion remarkable is not simply that it happened - individual converts have always found their way to the tribe - but that it was a sovereign decision by a ruling house, adopted as state policy. The Khazar kingdom subsequently had Jewish kings, Jewish officials, and a Jewish court life, while the general population continued to encompass Muslims, Christians, and pagans. The khagans were not demanding conversion of their subjects; they were practising their own faith at the top of a multi-confession empire, which may have been part of the political logic all along. A king who was neither Byzantine-Christian nor Abbasid-Muslim owed neither empire spiritual allegiance. The Torah was the faith of a people who had no empire to attach it to - which made it, for a steppe ruler who wished to remain independent, rather useful.
The record
Archaeological and numismatic evidence points to the Jewish character of the Khazar court. Coins minted in the Khazar orbit in the ninth and tenth centuries bear Hebrew letters and, in one series, the phrase Moses is the messenger of God - a deliberate echo of the Muslim Shahada, substituting Moses for Muhammad. A Hebrew inscription on a Khazar ring found in the Crimea, now in the collection of the Hermitage Museum in St Petersburg, provides additional material testimony. The Schechter Letter - a fragment discovered in the Cairo Geniza and published by the scholar Norman Golb and Omeljan Pritsak in their 1982 study Khazarian Hebrew Documents of the Tenth Century (Cornell University Press) - provides an independent Hebrew narrative of the conversion, naming the same Bulan and corroborating the broad outlines of the story King Joseph told Hasdai ibn Shaprut.
The Khazar kingdom fell to the Kievan Rus in 969 CE, a generation after the correspondence with Hasdai ibn Shaprut. What became of the Jewish Khazars is a question history cannot fully answer, and one that later centuries tried to answer in ways that served various agendas - most notoriously in Arthur Koestler's 1976 book The Thirteenth Tribe, which proposed that Ashkenazi Jews are largely Khazar descendants, a theory that population genetics has since comprehensively refuted. The Khazar story needs no such inflation. What it is, on its own terms, is extraordinary enough: a kingdom that looked at the three great faiths contending for the soul of the mediaeval world and chose the oldest, the smallest, and the one without an army behind it. That is not a footnote to Jewish history. It is one of its most arresting chapters.
The tribe has never needed an empire to carry it. The Khazars, for a season on the steppe, seem to have understood that. They picked the faith of a people who had survived without one, and they practised it with enough conviction that a Jewish king on the Volga was writing Hebrew letters to a Jewish minister in Cordoba two centuries later. The kingdom is gone. The correspondence is still here.
