The Khazar hypothesis of Ashkenazi ancestry, often called by its critics the "Khazar myth", is the hypothesis that Ashkenazi Jews are descended from the Khazars, a multi-ethnic conglomerate of Turkic peoples who formed a semi-nomadic Khanate in the area extending from Eastern Europe to Central Asia. The hypothesis draws on some medieval sources such as the Khazar Correspondence, according to which at some point in the 8th-9th centuries, the ruling elite of the Khazars was said by Judah Halevi and Abraham ibn Daud to have converted to Rabbinic Judaism. The scope of the conversion within the Khazar Khanate remains uncertain: the evidence used to tie the Ashkenazi communities to the Khazars is exiguous and subject to conflicting interpretations.