Germania Slavica
Germania Slavica is a historiographic term used since the 1950s to denote the landscape of the medieval language border (roughly east of the Elbe-Saale line) zone between Germanic people and Slavs in Central Europe on the one hand and a 20th-century scientific working group to research the conditions in that area during the Early Middle Ages and High Middle Ages on the other. The historian Klaus Zernack divides Germania Slavica into: Germania Slavica I between the Elbe and Saale rivers in the west and the Oder in the east, which had formed part of the Frankish and later Holy Roman Empires as marches Germania Slavica II east of Germania Slavica I and west of the Kingdom of Poland, comprising the Silesian, Pomeranian, and Prussian duchies as well as the Neumark.