The khazarian origin of ashkenazi jews theory came from the 19th century. Koestler may have found it useful for the purpose you mention but that doesn't invalidate the theory.

It's a historical fact the Khazar khaganate (modern day Ukraine) converted to judaism around 8th c. starting with Khan Bulan: https://en.wikipedia.org/wiki/Bulan_(Khazar) and were a jewish state until the russians came and destroyed them (history rhymes apparently).

We'll need a separate thread for that indeed.

The khazarian origin of ashkenazi jews theory came from the 19th century. Koestler may have found it useful for the purpose you mention but that doesn't invalidate the theory.

It's a historical fact the Khazar khaganate (modern day Ukraine) converted to judaism around 9th c. starting with Khan Zachariah: https://en.wikipedia.org/wiki/Zachariah_(Khazar) and were a jewish state until the russians came and destroyed them (history rhymes apparently).

We'll need a separate thread for that indeed.