Marwan II
Hazer Tarkhan was a general (tarkhan is both a military rank and, in some cases, a personal name) who led a Khazar army of 40,000 men in the failed defense of Atil in 737 CE. He was ambushed and killed by Kawthar, the lieutenant of Marwan ibn Muhammad (later Caliph Marwan II). Following his death the Khazars sued for peace.