Black Bulgaria

Kara Bulgar, or Black Bulgaria, succeeded Old Great Bulgaria and was ruled by Khan Batbayan and his successors. It emerged after Old Great Bulgaria broke up in 668 and became an autonomous vassal territory of the Khazar Khaganate. After Old Great Bulgaria's disintegration, the part under Batbayan became an autonomous Khazar vassal territory. For much of the seventh to tenth centuries, it was known as Black Bulgaria and its population as the Kara Bulgars.

In its early years, the Kara Bulgars and Khazars fought together against the Danubian Bulgars, the Arabs and Turkic tribes to the east. Their principal religion was Tengrism. In the mid-eighth century, following the Khazars' defeat by the Arab Caliphate in 737, the peoples of the Khazar Khaganate began to undergo Islamisation.

By the early ninth century, many Black Bulgars had adopted Islam. During Bek Obadiah's rule in Khazaria, however, Judaism became the official religion following the arrival of many Jewish preachers. Religious changes generated conflict, and in 820 Kara Bulgar's ruler, Urus Agar Aydar, rebelled against the Khazars. In 865, Kara Bulgar split into an eastern part, known as Volga Bulgaria, and a western part, still called Kara Bulgar or Black Bulgaria. In 895, Kara Bulgar's baghaturs attempted to reunite the two Bulgarias, but their effort was short-lived. Some historians date the end of the union to 922.

Towards the end of the ninth century, Kara Bulgar's last ruler, Árpád, became ruler of the Magyars and campaigned against Danubian Bulgaria. Tsar Simeon I and the Pechenegs inflicted a crushing defeat on Kara Bulgar. Some Black Bulgars and Magyars then moved to Pannonia and formed the Kingdom of Hungary, while others were assimilated by tribes from the east.

Kara Bulgar thus passed through several stages, from an autonomous vassal territory under Khazar supremacy to division into eastern and western parts and its end in the late ninth century.