Cika wannan magana: Ba a bayyana ba ko rabuwar hanyoyi ta 'yan'uwa ta haifar da rikice-rikice na ciki ko kuma matsin lamba mai karfi na Khazar. Wannan na biyun ya fi yiwuwa. 'Yan uwan biyu na farko Batbayan da Kotrag sun jagoranci' yan Bulgars sun kasance a cikin yankin Pontic steppe, inda aka san su da "Black Bulgars" ta hanyar Byzantine da Rus, kuma suka zama Khazars vassals. 'Yan Bulgarian da Kotrag ya jagoranta sun yi hijira zuwa yankin Volga na tsakiya a tsakanin ƙarni na 7 da na 9, inda suka kafa Volga Bulgaria, tare da Bolghar a matsayin babban birninta. A cewar Ahmad ibn Rustah (karni na 10), an raba Bulgars na Volga zuwa rassa uku: "an kira reshe na farko Bersula (Barsils), na biyu Esegel, kuma na uku Bulgar". A cikin 922 sun yarda da Islama a matsayin addini na hukuma. Sun kiyaye asalin ƙasarsu har zuwa ƙarni na 13 ta hanyar kawar da na farko
Harin Mongol a shekara ta 1223. Daga ƙarshe Mongols suka rinjaye su a 1237. A hankali sun rasa asalinsu bayan 1431 lokacin da Rasha ta kama garuruwansu da yankunansu.