As with other Bulanid rulers, it is unclear whether Isaac was Khagan or Khagan Bek of the Khazars, although the latter is more likely. He was succeeded by his son Zebulun. Historical authenticity and accuracy  of the only document mentioning his name has been questioned.
The status of Isaac as a ruler among other Bulanid leaders remains uncertain, whether he was a Khagan or a Khagan Bek of the Khazars, with the latter being more likely. He was succeeded by his son Zebulun. The credibility and accuracy of the only document referencing his name have been questioned.