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, bordering the Nordwestblock separating it from the La Tène culture proper farther south.
In 1577, he had to concede the revenue from Harpstedt, Delmenhorst, Varel and some minor castles to his younger brother Anthony II for a 10-year period.