>Turkic Bulgars didn’t appear in Balkan as horde, mostly probably just ruling class was Turkic, such as Asparuh.
Others are descedants mostly of Thracians and “Seven Slavic tribes” which was described there.
Oghur speaking Bulgars split into three groups. One group went to Danube, the other group went to middle Volga. Some Bulgars stayed in northern Caucases and Caspian steppes . Modern day Balkars living in northern Caucases derive their ethnonym from Bulgars. Danube Bulgars switched to Slavic language, while Finno-Ugric people of middle Volga – ancestors of Kazan Tatars and Chuvashes – switched to Oghur. Both Kazan Tatars and Chuvashes genetically relate to neighbouring Volgaic Finnic speaking Mari. Chuvashes also culturally relate to Mari in some ways.
During Golden Horde rule ancestors of Kazan Tatars and Balkars switched to Kypchak that was lingua franca in Horde at the time. The language that was spoken by nomadic Turkic living in western Kazakhstan. To this day Chuvashes speak Oghur – the language Bulgars spoke. There are numerous flame discussions between Chuvashes and Kazan Tatars fighting over Volga Bulgar heritage, which is funny to read. Today, Kazan Tatars speak Kypchak which can be understood by Kazakhs to some extent. Also many Kazan Tatars are russified unable to speak their native language, especially those living in cities and outside of Tatarstan.