Looking at the wikipedia site, it appears that the Battle of Ongal was the victory that marked the foundation of Danube Bulgaria, founded by Asparukh, while Volga Bulgaria is founded by Kotrag. Now what if Asparukh were to die somehow between the fragmentation of Old Great Bulgaria and the Battle of Ongal itself? Which Slavic entity would be in position to replace *Bulgaria, and would they be a good substitute? Alternatively, would the Seven Slavic Tribes of Moesia actually create their own state as well?