At the end of World War II, the Soviet Union annexed most of the territories it had invaded in 1939. Some parts of eastern Poland occupied by the Nazis in 1939 with an area of 21,275 square kilometres (8,214 sq mi) and 1.5 million inhabitants near Białystok and Przemyśl were returned to postwar Poland.[31] The Western Allies were unaware of the existence of the secret clause dividing Poland between Hitler and Stalin already in 1939 along the Curzon Line.[32]