In the treaty, both sides committed themselves to nonviolence and accepted the existing border - the Oder-Neisse line. This was a very sensitive topic at the time as Poland was concerned that one day a German government would lay claim to some of the territory Germany lost after World War II. Poland took over this territory to replace eastern Poland, which the Soviet Union had conquered in 1939. A lot of that land was east of the Curzon Line, and Poland kept it after the Polish-Soviet War (1919-1921).