The Khazar theory claims that European Jews are the descendants of Khazars, a Turkic people who lived in Eastern Europe and Central Asia, rather than from Jews who originated in the Middle East.

Absolute insanity – Palestinian President Mahmoud Abbas distorts Holocaust, invokes white supremacist Khazar theory, says MENA Jews did not want to leave their Arabic countries of residence but ...

Fast Forward Jersey City Shooter Believed Khazar Anti-Semitic Conspiracy Theory Graphic by Angelie Zaslavsky By Aiden Pink December 17, 2019 ...

I have no idea what the "Khazar theory" is and I am certainly not about to pollute my browsing history with the things you mention. Incidentally one strand of my own ancestry is Southern Jewish ...

The better question is probably this: Why is the Hebrew component in Yiddish so large? I know of two answers that have been offered to this question. One of them might be called the Khazar theory.