Yeah... No.
What you are saying is extremely oversimplified and not quite convincing.
You are lumping together Germanic tribes, Goths with Thracians.
http://news.nationalgeographic.com/n...garia-science/
Just like the the author of the Getica who claimed Goths and Getae are the same people.
Also what is Slavic? There is a Slavic culture, but not really a Slavic ethnicity.