 After Germany and the Soviet Union had partitioned Poland in 1939, following their invasion, most of the ethnically Polish territory ended up under German control while the areas annexed by the Soviet union was ethnically diverse peoples with the territory being divided into several areas some of which had a significant non-Polish majority (Ukrainians in the south and Belarusians in the north), many of whom felt alienated in the interwar Poland and welcomed the Soviets.Nonetheless Poles composed the largest single ethnic group on the territories annexed by the Soviets.By the end of the Polish Defensive War the Soviet Union had taken over 52.1% of the territory of Poland (circa 200,000 km²), with over 13,700,000 people.