This article traces the development of the Khazar Hypothesis - the claim that Ashkenazi Jews descend primarily or substantially from medieval Khazar converts to Judaism rather than from ancient Israelite populations - from its earliest modern formulations through contemporary genetic and historical scholarship. For the main topic, see Khazar Hypothesis. For scientific and historical assessments of the claim's validity, see Khazar Hypothesis - Genetics Consensus and Khazar Hypothesis - Historical Consensus.
Awareness of the Khazars as a Turkic or mixed steppe people who converted to Judaism in the early medieval period entered European scholarship gradually. Johann Jakob Schudt (1664-1722), a German Christian Hebraist, noted the Khazar conversion in his Jüdische Merkwürdigkeiten (1714-1718) without drawing demographic conclusions about contemporary Jewish populations. Similarly, early orientalists and travellers who encountered references to the Khazars in Arabic and Hebrew sources treated the conversion as a historical curiosity rather than a challenge to Jewish genealogical continuity.
The Danish historian Andreas Schultens and later scholars working on medieval Islamic geographers - particularly the accounts of al-Masudi and Ibn Fadlan - helped establish Khazar history as a legitimate area of European philological inquiry during the 18th century. The 10th-century Hebrew Kuzari Letter, a correspondence purportedly between the Khazar king Joseph and the Spanish Jewish dignitary Hasdai ibn Shaprut, was published and discussed by scholars including Johann Christoph Wolf, lending textual weight to accounts of the Khazar conversion.
Ernest Renan and other 19th-century racial theorists occasionally referenced the Khazars in discussions of Jewish origins, though none mounted a systematic argument that Ashkenazi Jews were primarily Khazar in descent. The groundwork for such an argument awaited 20th-century synthesis.
The earliest sustained scholarly argument connecting Khazar descent to Ashkenazi Jewish origins appeared in the work of the Polish-Jewish historian and publicist Yitzhak Schipper (1884-1943). Writing in the early decades of the century, Schipper proposed that the Jewish communities of Eastern Europe had been augmented - possibly substantially - by the descendants of Khazar converts. His argument drew on demographic anomalies: the apparent difficulty of accounting for the large medieval and early modern Ashkenazi population solely through migration from Western and Central Europe.
The Russian-Jewish historian Abraham Eliyahu Harkavy had earlier examined Hebrew and Arabic sources on the Khazars, and various Russian imperial-era scholars contributed philological and archaeological work that would later be incorporated into the hypothesis. Within Russia and the Soviet Union, interest in Khazar history carried additional valence given the geography of the former Khazar polity and the large Jewish populations of the Pale of Settlement.
The hypothesis remained confined largely to specialist historical debate until the Hungarian-British author Arthur Koestler published The Thirteenth Tribe in 1976. Koestler drew on existing scholarly literature - including the work of Schipper and the Israeli historian D.M. Dunlop, whose 1954 History of the Jewish Khazars was a standard academic treatment - and argued for a popular audience that the bulk of Ashkenazi Jewry descended from Khazar converts rather than from the ancient tribes of Israel.
Koestler's motivations, as stated in the book itself, included the hope that severing a genealogical link between contemporary Jews and ancient Israelites might reduce antisemitism by undercutting claims of Jewish racial distinctiveness or territorial entitlement. The Thirteenth Tribe became a bestseller and introduced the Khazar hypothesis to a mass readership well beyond academic circles.
Professional historians and physical anthropologists received the book critically. Dunlop himself, whose scholarship Koestler drew upon, expressed reservations about the demographic extrapolations. Critics noted that Koestler's argument rested on inference and analogy rather than direct documentary or biological evidence.
Following the publication of The Thirteenth Tribe, the Khazar hypothesis was taken up by a range of non-academic constituencies. Arab nationalist writers and some Palestinian political figures cited Koestler to argue that Zionist claims to the Land of Israel rested on false genealogical premises - that Ashkenazi Jews had no ancestral connection to the region. white nationalist and neo-Nazi groups in the United States and Europe similarly circulated the hypothesis, using it to argue that Ashkenazi Jews were not a distinct semitic people but rather a Turkic or mixed Central Asian population.
These adoptions were largely independent of, and often at odds with, mainstream historical scholarship. Academic historians of the medieval period continued to study the Khazars on their own terms. Works by Peter Golden, Thomas Noonan, and others developed a more nuanced picture of the Khazar polity, its conversion - likely partial and elite-centered rather than population-wide - and its eventual collapse following Rus and Pecheneg military pressure in the late 10th century.
The Israeli historian Shlomo Sand revived popular interest in the hypothesis with The Invention of the Jewish People (Hebrew original 2008, English translation 2009). Sand argued that modern Jewish national identity rested on constructed or mythologized genealogical claims, and incorporated a version of the Khazar hypothesis as part of a broader argument about the discontinuity between ancient Israelites and contemporary Jews. The book was a commercial and polemical success and generated substantial controversy in Israel and internationally.
The development of population genetics provided a new empirical dimension to the hypothesis beginning in the early 2000s. Studies using mitochondrial DNA, Y-chromosome markers, and eventually genome-wide autosomal analysis examined the ancestry of Ashkenazi Jewish populations and their relationships to Middle Eastern, European, and Central Asian populations.
A series of studies - including work by Harry Ostrer, Gil Atzmon, Doron Behar, and colleagues published in journals including Human Genetics and Nature - consistently found that Ashkenazi Jews clustered genetically with other Jewish diaspora populations and showed significant shared ancestry with Middle Eastern populations, particularly those from the Levant. These studies found little evidence of substantial Khazar or broader Central Asian genetic contribution.
A 2012 study by Eran Elhaik, published in Genome Biology and Evolution, challenged this consensus. Elhaik argued that his analysis of autosomal genetic data showed Ashkenazi Jews to be more closely related to Caucasian and Iranian populations than to Levantine populations, and interpreted this as supporting a Khazar origin. The study received wide media coverage and was cited by proponents of the hypothesis.
Other population geneticists disputed Elhaik's methodology and conclusions, arguing that his reference populations and statistical methods were unsuitable for the inference he drew. Subsequent large-scale studies, including work using ancient DNA from archaeological sites, continued to support substantial Levantine ancestry among Ashkenazi Jews alongside evidence of admixture with Southern European populations during the diaspora period.
Some historians argue that the Khazar conversion was broader and more demographically significant than elite-conversion accounts suggest; for competing assessments see Khazar Hypothesis - Historical Consensus.
The extent to which Koestler's political motivations shaped his historical argument is disputed; see Khazar Hypothesis - Koestler's Intent Viewpoint.
Whether Elhaik's 2012 genetic study constitutes a credible challenge to the mainstream genetic consensus or reflects methodological error is contested among population geneticists; see Khazar Hypothesis - Genetics Consensus and Khazar Hypothesis - Elhaik Viewpoint.
The relationship between political interest in the hypothesis - from nationalist, antisemitic, and anti-Zionist sources - and the reception of scholarly arguments for or against it is disputed; see Khazar Hypothesis - Debate.