After the war, a large number of Poles were forced to move to Poland. In exchange, Belarusians from the former Belastok Voblast, which was returned to Poland in 1945, after being occupied in 1939 were displaced to Belarus. Due to changes in the western border of Belarus and Poland after World War II (see territorial changes of Poland), the number of Poles in Belarus increased to more than 500,000 according to the first post-war census (1959) and to about 400,000 according to the 1999 census. Poles are now the third largest ethnic group in Belarus (see Polish minority in Belarus). There are around 15,000 of Lipka Tatars and about 10,000 of Ruska Roma (Russian Gypsies).