Probably just ignorance, but there actually was a gap in that time in some areas in germany. Close to my hometown are the remains of an old ancient fortress - that was build by mostly unknown people and abandoned at 400 b.c. and only 1000 years later there were settlements again. A bit rougher area, though.
replyThe flat area of Berlin on the other hand, had human settlement since 60 000 years.
I don't think anyone requires every hectare to have been developed in order to consider an area inhabited. Neanderthals are named after the Neander valley (Thal) near Dusseldorf, so I think we can definitely say yes, that humans have lived in Germany since long before antiquity.
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