Yeah, pretty much this. The problem with modern theories on the disapora of the Germanic language family is that the divisions linguists have perceived in their models and comparative studies (namely, the division of Germanic into Ingvaeones, Istvaeones, and Irminones) has little to no correlation to any anthropological or archaeological data so far constructed. For the most part correlating language groups to defined archaeological cultures, while interesting, is, at least among Germanic languages, a rather pointless affair.
But there are theories which say that Germanic languages were not present in area inhabited by peoples of the Lusatian Culture at all. Or if they were present, then only in the Western part of this area. According to a book "Historia Polski" ("History of Poland") by prof. Jerzy Lesław Wyrozumski, Germanic tribes migrated to areas of modern Poland not before the 1st century AD. And the Lusatian Culture is much older - it dates back to the Bronze Age. According to Wyrozumski the Goths and the Gepidae arrived in the basin of lower Vistula (area of Northern Poland) at the beginning of the Common Era, and then by the end of the 2nd or the beginning of the 3rd century they migrated further towards the Black Sea, from where later (5th century) under the names of Visigoths and Ostrogoths, they marched westward and crossed the border of the Roman Empire. The Gepidae followed the Goths in the middle of the 3rd century AD, also towards the Black Sea.
Wyrozumski writes:
"(...) The presence of the Goths and the Gepidae in these areas was just an episode. They did not displace local Slavic population from this area, even though it is probable that they managed to temporarily subordinate it. (...)"
The source for the arrival of the Goths into area of modern Northern Poland is the Gothic historian Jordanes (lived in 6th century AD). Archaeological source for their arrival to the Lower Vistula basin, are skeletal burials - common for Germanic tribes, but not practised by local population of this area at that time.
Then he writes:
"(...) Historiography - especially German - has discerned on lands of modern Poland also the presence of other Germanic tribes - basing on writings of Tacitus and Ptolemy. Those were the Burgundians, the Lugiones, the Vandals, the Hasdingians and the Silingians. Regarding the Burgundians, there is some probability that temporarily and in small numbers they could appear in the south-western part of lands of modern Poland, however - they did not leave any undisputed traces of their presence. Regarding the Lugiones - most probably they were not a Germanic tribe, but rather a Celtic one, and inside the range of their settlement was mainly Lusatia and partially Silesia. It is possible that the Vandals temporarily settled in Silesia during their migration from Scandinavia, before they continued their movement towards Italy and Spain. But premises of this supposition are very tenuous. It is also supposed, that a tribe of the Hasdingians, which was part - as is assumed - of a tribal union of the Vandals, could also temporarily settle in Silesia. When it comes to the Silingians, who were also part of the same tribal union, German historians assumed that the name of Silesia originated from them, so they considered their presence in this part of Poland as a fact. However, there is no any source, historical or archaeological premise, which would justify such a conclusion. The name of Śląsk is indigenously Slavic (from ślęż = swampy area) and this finds toponomastic confirmation in the mountain Ślęża and the river Ślęża, as well as the fact that in the area of this river and this mountain lived the Slavic tribe of Ślężanie, confirmed by written sources in the 10th century. It seems more probable that Silingians temporarily lived in the area of Lusatia. (...)"
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Interesting recent genetic studies:
http://translate.google.pl/translat...a=X&ei=1xAQUYnmEOP_4QTNt4HgCA&ved=0CDwQ7gEwAQ
http://translate.google.pl/translat...a=X&ei=1xAQUYnmEOP_4QTNt4HgCA&ved=0CFQQ7gEwBA
http://translate.googleusercontent....6719,4&usg=ALkJrhgrUzcKTtf_RBvGgw-V_qp2MX-mTg