What if Old Great Bulgaria wasn't conquered by the Khazars? How might things be different?
if the sons of Kubrat still split we would have 3 Bulgarian kingdoms Volga, OTL and Crimea with the latter 2 probably merging later. IF OGB survives they will convert to orthodox and maybe even the Volga one instead of Muslim.
let's say that the mongol invasion just makes them tributaries. while Volga Bulgaria will probably die as OTL
the Enourmous Bulgarian empire( from Macedonia to Budapest to Crimea) will be for sure able to take Constantinople if stable enough but there are already too much divergences so don't know, after all i'm taking as example "only" 500 years( 600-1100 AD).
IF it collapses as OTL and the rest goes almost the same The biggest difference might be no walacchians/moldavians( melted with bulgarians) and thus when bulgaria is freed will have enourmous claims or as OTL but with a lot of bulgarians speaking across balkans-crimea