Theory re Origins in Khazaria

Based on the beliefs that R1a1a Ashkenazi Levites appear to share a Most Recent Common Ancestor ("MRCA") who lived only about 1,000 years ago and that there are few R1a1a Levites among the Sephardim, some researchers have speculated that R1a1a Ashkenazi Levites are descended from a convert to Judaism, perhaps royalty or nobility from the kingdom of Khazaria or a member of another non-Jewish European group.  

Other researchers believe that the R1a1a Ashkenazi Levite progenitor may have been descended from a Jewish man whose line had almost become extinct, pointing out that Jewish religious tradition precludes known converts from becoming Levites. 

The Khazarian theory was popularized by Arthur Koestler in his book The Thirteenth Tribe (1976), where he hypothesized that the Ashkenazi population is descended from the Khazars, a Turkic people who lived in the area north of and between the Black Sea and the Caspian Sea, now the western part of Kazakhstan.  

The Khazars – or, at least, the Khazarian royalty and nobility – are said to have converted to Judaism in the 8th century in order to preserve their neutrality as between neighboring Christian and Muslim empires.
[1]  

Koestler hypothesized that some of those converts migrated from Khazaria west to Eastern Europe in the 11th and 12th centuries, as the Kingdom of Khazaria collapsed, and established the Ashkenazi population. 

The pioneering 2003 Y-DNA study on Ashkenazi Levites by D. Behar et al. observed, based on the then-available data and methodologies, that R1a1 is very common among Ashkenazi Levite populations but relatively uncommon among other Jews. Behar et al. posited that R1a1a Ashkenazi Levites may be descendants of “a founder(s) of non-Jewish European ancestry, whose descendants were able to assume Levite status.”
  

While Behar et al. noted in the 2003 study that the genetic evidence was not “consistent with a major Khazar or other European origin” for Ashkenazi Jews, they stated that one could not rule out the possibility that one or a small group of Khazars might have been the founder(s) of R1a1a Ashkenazi Levites.  
 
Behar et al. suggested in the 2003 study that it may have been possible for a man to assume Levite status other than through patrilineal descent. Other writers have suggested that the royalty or nobility of Khazaria could have assumed Levite status in Khazaria, despite Jewish law requiring patrilineal descent for Levite status, allowing them to retain such status if and when moving to Europe.

In their 2013 study, Rootsi & Behar et al. found, based upon newly gathered Y-DNA SNP data from R1a1a Ashkenazi Levites, R1a Europeans, and R1a Near Eastern males, that "the current data are indicative of a geographic source of the Levite founder lineage in the Near East and its likely presence among pre-Diaspora Hebrews," and that the data do not appear to support origins in Europe or Khazaria.

Kevin Alan Brook’s Khazaria.com website provides a comprehensive discussion of the Jews of Khazaria, as well as links to other resources. 

Professor Shaul Stampfer has published an article, downloadable here, concluding that there is no reliable historical evidence - or any archaeological evidence - of a conversion of Khazars to Judaism.

Click here for a summary of recent articles addressing the issue whether autosomal DNA supports the Khazarian theory, and an open letter from Anatole Klyosov discussing the issue. 

In a 2017 paper, Professor Klyosov detailed the results of Y-DNA testing of the excavated bone remains of two Khazars whom, although R1a-Z93 like R1a-Y2619 Ashkenazi Levites, did not belong to the R1a-Y2619 cluster; their shared direct male ancestor with R1a-Y2619 Ashkenazi Levites lived about 8,000 years ago.

[1] The Jews of Khazaria have long fascinated Jewish scholars. In 1140 in Spain, Rabbi Yehuda Halevi wrote, in Arabic, a booklet entitled Book to Defend a Humiliated Religion; in 1265 in Lunil, Provence, Rabbi Yehuda ben Tibon, a Levite scribe from a famous family of translators, translated the booklet to Hebrew, naming it Sefer HaKuzari (in English, Book of Khazaria).

That booklet, written in the Talmudic methodology of question and answer dialogue, sets forth a discussion between Bulan, King of Khazaria – who was searching for a new religion for his people – and a Jew identified as “the friend.” (In Sefer HaEmunot, written in 1488, Shem Tov ben Shem Tov Kalonymos identified Itzhak Al-Mangeri (the man from Mangeria) as “the friend”; later works identify the man as Itzhak HaSangeri (the man from Sangeria, a region in Iberia), presumably because of the believed link between the Khazarian Jews and Spain.)

Rabbi Yehuda Halevi (who was believed to be an ancestor of the Horowitz rabbinical family by Rabbi Zvi Halevi Horowitz, a rabbi in Dresden, Germany during the 1930s) apparently based his booklet on an essay about Khazarian history written in about 949 CE by a Jew from Khazaria; that essay, a copy of which was discovered in 1896 in the Cairo Geniza, a trove of Jewish manuscripts found in a storeroom at a Cairo synagogue, is now known as the Schecter Letter or the Cambridge Document.

According to a work written in 1061 by Rabbi Yehuda Halevi’s contemporary Abraham ibn Daud, rabbinical students descended from the Khazars were studying in Toledo, Spain during his lifetime. Rabbi Yehuda Halevi lived in Toledo at various times during his life.
Jacob Wald

Jakob Wald (1878-1942)
Photograph taken in @1915 in 
Nagyvárad, Austria-Hungary 
(now Oradea, Romania)
Kuzari.Wien.1796.t.p.
Title page from 1796 edition of HaKuzari, published in Vienna

Jim Wald has provided us with photographs of editions of
HaKuzari, published in Vienna in 1796 (signed by a Jakob
Horowitz), in Warsaw in 1866, in Leipzig in 1869, in