Not totally, only partially. At the time the Bulgarians were already a mix of the Slavic, Byzantine, and other peoples - including, of course, the Bulgars who,

Not totally, only partially. At the time the Bulgarians were already a mix of the Slavic, Byzantine, and other peoples - including, of course, the Bulgars who, too, settled there, in the process of their migration from the East. The Bulgarian language and the Bulgar language have little (if anything) to do with each other.