Ostsiedlung

Ostsiedlung, literally "settlement in the east", also called German eastward expansion, was the medieval eastward migration and settlement of Germans from modern day western and central Germany into less-populated regions and countries of eastern Central Europe and Eastern Europe. The affected area roughly stretched from Slovenia to Estonia, and eastwards into Transylvania. In part, Ostsiedlung followed the territorial expansion of the Holy Roman Empire and the Teutonic Order.