How did Bulgaria form?

Answer 1

Uniting in one country (one of the oldest European countries) the old Bulgarians (so called proto-Bulgarians), some of the Slavs and the Thracians (maybe the oldest civilization in Europe before Greece).

addition:

Han Asparukh first conqured the local slavs (славяни), later the mizians (мизии)

and forced them to accept the rule of the pre-bulbarians (prabulgarians-Прабългари). Later he orderd his own tribe to be merged (to make marriage unions with the slavs and to learn agriculture from them)

Answer 2

Han Asparukh, warrior was searching for some new land to rule and eventually settle. It was 681 AD. He started his journey, crossed Daniube and reached to the Black sea. He had no means how to cross the sea. Moreover his soldiers were tired after a long journey. Hospitality of the local slavs was another factor to decide to settle. Slavs were good in agriculture. They produced enough grains and wine. So, the great <han> Asparukh settled. Asparukh named his conqured territory as Bulgaria.