http://en.wikipedia.org/wiki/Zebulun_(Khazar)

Zebulun (Khazar)

Zebulun or Zevulun ben Isaac was a Jewish Turkic ruler of the Khazars mentioned in the Khazar Correspondence. He probably reigned in the late ninth century CE. Little is known about Zebulun's reign. As with other Bulanid rulers, it is unclear whether he was Khagan or Khagan Bek of the Khazars, although the latter is more likely.