Gravefields in today's Schleswig-Holstein, Mecklenburg, western Pomerania, in Brandenburg and in Lower Saxony show continuity of occupation from the Bronze Age far into the Jastorf period and beyond.
This was helped or propitiated by the earlier vacancy or large depopulation of these areas, as it became known in the archaeological record and from Classic sources that local Hallstatt Culture groups considered Celtic or Belgian (more or less Celtic) migrated in its D period to extensive areas further West and South as far as the Mediterranean and Atlantic Europe.
In its mature phase, the Jastorf area proper in northern Lower Saxony (Lüneburger Heide, lower Elbe) can be contrasted with the so-called Nienburg (also Harpstedt-Nienburg) group to the west, situated along the Aller and the middle Weser rivers, bordering the Nordwestblock separating it from the La Tène culture proper farther south.
The southernmost extent of Germanic cultures beyond Jastorf has recently been accounted for at the final stages of the Pre-Roman Iron Age, with the paucity of Late-La Téne bracelet-types in Thuringia and northeastern Hesse proposed to suggest population movements between the central-Elbe/Saale region, Main-Franconia and the edge of the Alps and to have been triggered by the spread of the Przeworsk culture.
[4] The demographic vacuum left in the south of Germany around the upper Danube and Rhine rivers, by the migrations of Celtic groups hitherto there into much richer lands in Gaul, Spain, Pannonia and Northern Italy from 400 BC probably also played a role.