Khazar kingship was divided between the khagan and the Bek or Khagan Bek.
The Khazar heartland was on the lower Volga and the Caspian coast as far south as Derbent.
Khazar rabbinical students are known to have studied in Spain from the accounts of Abraham ibn Daud, and Jews from Kiev and elsewhere in Russia, who may or may not have been Khazars, were reported in France, Germany and England.