Do you buy into the Hypothesis that the Khazars all converted to Judaism at one time,
Not all Khazars was converted to Judaism. In most khaghanats Judaism was a religion of authorities. However, in Khazar khaganat, Judaism get much more spread into lower classes. I don't know real percentage, but could assume one third or half of population.
and they were not descended from Abraham?
I don't know. However, the theory that Khazars are ancestors of Ashkenazi is valid and even officialy accepted theory.
After the rout of Khazar Khaghanat by Russian army leaded by duke Svyatoslav in 965, part of khazars run to Europe and become Ashkenazi jews.
Not all Khazars was converted to Judaism. In most khaghanats Judaism was a religion of authorities. However, in Khazar khaganat, Judaism get much more spread into lower classes. I don't know real percentage, but could assume one third or half of population.
I don't know. However, the theory that Khazars are ancestors of Ashkenazi is valid and even officialy accepted theory.
After the rout of Khazar Khaghanat by Russian army leaded by duke Svyatoslav in 965, part of khazars run to Europe and become Ashkenazi jews.