When discussing such matters, one should be cautious when using cathegories that only make sense within a contemporary mindframe. If we want to talk about the origins of Germany as a nation, then we can go back no further than the late XVIII / early XIX centuries, if we want to talk about the start of Germany as a distinct, more or less unified and self-conscious political entity, again we can go back no further than the death of Louis the Pious in 843. Earlier than that, the only thing we can talk about (barely a bit above guessing) is about the probable evolution of Germanic languages, and that keeping in mind that other than Ulfilas' Gospel, some liturgical hymns and some runic graffiti, we have to rely entirely on isolated words transcripted by Roman or Greek authors (from the I century AC onwards). Further than that, we have absolutely no way to be sure about anything, other than to trust the validity of contemporary theories about the evolution of languages.
And if that's true about the Germans, who spent a long time in direct contact with the Greco-Roman culture, it's even worse for the Huns and Bulgars, about whom we can only rely on archaeological evidence.
It's fairly dubious that the Goths, Burgundians and Vandals that invaded the Roman empire were anything like a unified, self-conscious ethnic unity, and the same can be said about the Huns and Bulgars. It's not even been completely settled if they were or not Turkic peoples, and also it's doubtful if they were really related to the Xiong-nu described in ancient Chinese chronicles. Even having the archaeological evidences provided by the "Xiong-nu" graves excavated in modern Mongolia and being able to compare them with the remains unearthed from supposedly "Hunnic" graves from the IV-VI centuries AD Eurasian steppe, professional archaeologists and historians have not been able to reach a consensus.