The original Bulgars were Turkic tribes of Oghur origin, who settled north of the Black Sea. During their westward migration across the Eurasian steppe, they came under the overlordship of the Khazars, leading other ethnic groups, including Finno-Ugric and Iranic peoples. About 630 they founded Old Great Bulgaria which was destroyed by the Khazars in 668. Kubrat's son and appointed heir Batbayan Bezmer moved from the Azov region in about AD 660, commanded by the Kazarig Khagan Kotrag to whom he had surrendered. They reached Idel-Ural in the eighth century, where they became the dominant population at the end of the 9th century, uniting other tribes of different origin which lived in the area. Some Bulgar tribes, however, continued westward and eventually settled along the Danube River, in what is now known as Bulgaria proper, where they created a confederation with the Slavs, adopting a South Slavic language and the Eastern Orthodox faith.