According to the decisions of the Potsdam Conference most of the former German territories east of the Oder-Neisse line were placed under Polish administration and most of the remaining German population was expelled . Some of those territories had historical ties with Poland , dating to the medieval fragmentation of Poland in the Duchy of Silesia , but were also populated by German-speaking inhabitants for many centuries
Potsdam Conference
Potsdam Conference
Commission for the Determination of Place Names