Maybe pgtx will leave my links alone this time...
...During the Iron Age, Western Pomerania belonged to the Jastorf culture (550-50 BC). As before during the Bronze Age, the dead were burned and the ashes buried in urns. Settlements and urn grave fields with artefacts were found e.g. in the then densely settled Greifswald area.
The Jastorf culture is associated with early Germanic peoples.Western Pomerania belonged to the Warnow-Oder estituary subgroup of the Jastorf culture, the easternmost group is designated Oder group. The Oder group, formerly thought to have emerged after an immigration from Bornholm, is now thought to have evolved from a local population formerly belonging to the Pomeranian culture and the Göritz group of the Lusatian culture, who first adapted to new habits and later mingeld with a Germanic population from the West....
German since 500 BC
...It is assumed that Burgundians, Goths and Gepids with parts of the Rugians left Pomerania during the late Roman Age, and that during the migration period, remnants of Rugians, Vistula Veneti, Vidivarii and other, Germanic tribes remained and formed units that were later Slavicized.[14
Then slavicized Germans....(assumed). Now who was the invader?