Territories of Poland annexed by the Soviet Union

These annexed territories were subsequently incorporated into the Lithuanian, Byelorussian, and Ukrainian Soviet Socialist Republics and remained within the Soviet Union in 1945 as a consequence of European-wide territorial rearrangements configured during the Tehran Conference of 1943 (see Western Betrayal). Poland was compensated for this territorial loss with the pre-War German eastern territories, at the expense of losing its eastern regions. The Polish People's Republic regime described the territories as the "Recovered Territories". The number of Poles in the Kresy in the year 1939 was around 5.274 million, but after ethnic cleansing in 1939-1945 by Nazi Germany, the Soviet Union and Ukrainian nationalist forces consisted of approximately 1.8 million inhabitants.^[1] The post-World War II territory of Poland was slightly smaller than the pre-1939 land areas, shrinking by some 77,000 square kilometres (30,000 sq mi) (roughly equalling that of the territories of Belgium and the Netherlands combined).

These areas were conquered by Nazi Germany in 1941 during Operation Barbarossa. The Nazis divided them up as follows:


During 1943–1944 ethnic cleansing operations took place in Ukraine (commonly known as the Massacres of Poles in Volhynia) which brought about an estimated 100,000 deaths and an exodus of ethnic Poles from this territory.


The Polish and Jewish language population of the regions in 1939 totaled about 6.7 million. During the war, an estimated 2 million persons perished (including 1.2 million Jews). These numbers are included with Polish war losses. 2 million (including 250,000 Jews) became refugees to Poland or the West, 1.5 million were in the territories returned to Poland in 1945 and 1.2 million remained in the USSR.^[32] Contemporary Russian historians also include the war losses of Poles and Jews from this region with Soviet war dead.^[33]