According to the genetic studies which we here now discuss bulgarians are slavs with some thracian elements. And it's abosuletly true. Most of the thracians are asimilated by the romans and greeks, but there are those of them who do stay in the bulgarian lands during the invasion of 4-5 cen. AD.
And although the byzantine hronologists say that the balkans were devastated and ethically cleaned there are some thracian tribes wich were asimilated by the slavs from the dacian(bulgarian) group. But according to the bulgarian istoriography,folklorists, linguists and now scientists we are part of the slavic family;D