A cikin 632, Khan Kubrat ya haɗu da manyan kabilun Bulgar uku mafi girma: Kutrigur, Utugur da Onogonduri, ta haka ne aka kafa ƙasar da a yanzu masana tarihi ke kira Great Bulgaria (wanda aka sani da Onoguria).Wannan ƙasa tana tsakanin ƙananan hanya na kogin Danube zuwa yamma, Bahar Maliya da Tekun Azov a kudu, kogin Kuban zuwa gabas da kogin Donets a arewa.Babban birnin shi ne Phanagoria, a kan Azov.A cikin 635, Kubrat ya sanya hannu kan yarjejeniyar zaman lafiya tare da sarki Heraclius na Daular Byzantine , yana faɗaɗa mulkin Bulgar zuwa cikin Balkans.Daga baya, Kubrat ya samu rawani da lakabin Patrician ta Heraclius.Masarautar ba ta tsira daga mutuwar Kubrat ba.Bayan yaƙe-yaƙe da yawa da Khazars, daga ƙarshe aka ci nasara a Bulgars kuma suka yi ƙaura zuwa kudu, zuwa arewa, kuma galibi zuwa yamma zuwa cikin Balkans, inda mafi yawan sauran kabilun Bulgar ke zaune, a cikin ƙasa mai mulkin mallaka zuwa Daular Byzantine. tun daga karni na 5.Wani magajin Khan Kubrat, Asparuh (dan uwan ​​Kotrag) ya koma yamma, ya mamaye kudancin Bessarabia a yau.Bayan yakin da aka yi da Byzantium a shekara ta 680, Asparuh's khanate ya ci nasara a farko Scythia Minor kuma an amince da shi a matsayin kasa mai cin gashin kanta a karkashin yarjejeniyar da ta biyo baya da aka rattabawa da Daular Byzantine a shekara ta 681. Ana daukar wannan shekarar a matsayin shekarar kafuwar Bulgaria ta yau. kuma ana daukar Asparuh a matsayin shugaban Bulgaria na farko.