Batbayan-Bezmer was placed in charge of the Bolgars by Chouvrtou but was overthrown in 677. He retreated to Carpathia consolidating his rule around Cuzdrioara , Ungvar and Halych. He seems to have been descended from the Aba clan making him the ancestor of Bulan. He and his descendants after him remained loyal to the Kara-Khazars converted to Judaism under Bulan whose descendants were the Kiabar-Cozars in Kopyriv Kinets'.