Bulan was a Khazar king who led the conversion of the Khazars to Judaism. His name means "elk" or "hart" in Old Turkic. The date of his reign is unknown, as the date of the conversion is hotly disputed, though it is certain that Bulan reigned some time between the mid-8th and the mid-9th centuries. Nor is it settled whether Bulan was the Bek or the Khagan of the Khazars. His wife, Serakh, is described as a Jew and as encouraging him to study and adopt Judaism. The Schechter Letter is silent on the issue of whether Sabriel was Bulan; the name Bulan does not appear in that document.