Page "History of Israel" Paragraph 41

In 611, Sassanid Persia invaded the Byzantine Empire and, after a long siege, Chosroes II captured Jerusalem in 614, with Jewish help, including possibly the Jewish Himyarite Kingdom in Yemen.

Jews were left to govern Jerusalem when the Persians took over, though the short living Jewish commonwealth lasted until about 617, when the Persians capitulated.

The Byzantine Emperor, Heraclius, promised to restore Jewish rights and received Jewish help in defeating the Persians, but he soon reneged on the agreement after reconquering Palestine by issuing an edict banning Judaism from the Byzantine Empire.

( Egyptian ) Coptic Christians took responsibility for this broken pledge and still fast in penance.

Jews fleeing Byzantium settled in the Baltic area, where the Khazar nobility and some of the population subsequently converted to Judaism.