The state of Prussia was '' de jure '' abolished in 1947 after the defeat of Nazi Germany in World War II ; the was replaced with the Brandenburg . Territory east of the Oder – Neisse line ( the region ) was placed under Polish administration ( became part Poland as her boundaries were agreed by the international powers in 1945 at the Yalta Conference ) and separated from Germany . Most of its German-speaking population was expelled and replaced with Poles . Brandenburg west of the Oder – Neisse line lay in the Soviet occupation zone ; it became part of the German Democratic Republic . In 1952 the region was divided among the districts of Cottbus , Frankfurt ( Oder ) , Potsdam , Schwerin , and ; Berlin was divided between East Berlin and West Berlin
Yalta Conference
Yalta Conference
Margraviate of Brandenburg