[Verginius Rufus]

Arthur Koestler was of Jewish descent, at least on his mother's side. Apparently he thought that he was combatting European anti-Semitism by arguing that Ashkenazi Jews are descended from the Khazars rather than from the ancient Israelites. There is some historical evidence for some Khazars converting to Judaism in the Middle Ages.

From what I have read, DNA testing has turned up zero evidence of any Khazar ancestry among modern Ashkenazi Jews, but plenty of evidence connecting them with the southern Levant--the Holy Land.

[Pelham]

Some might assume that Koestler’s “descended from the Khazars” theory was based on some sort of animus against Jews but in fact he intended it as a counter to racial anti-Semitism. Koestler himself was a non-practicing English Jew, born in Hungary. His two autobiographical volumes are very good.