The Holocaust saw the ghettoization, robbery, deportation and mass murder of Jews in occupied Poland by Nazi Germany. Over three million Polish Jews were murdered, primarily at the Chełmno, Belzec, Sobibor, Treblinka and Auschwitz extermination camps, who made up half of the Jewish Holocaust victims.
During Nazi occupation, the country lost 20% of its population, or six million people, including three million Jews (90% of the country's Jewish population). In 1939, Nazi Germany invaded Poland while the Soviet Union invaded Poland from the east. In German-occupied Poland, Jews were killed, subjected to forced labor, and forced to move to ghettos. Some 7,000 Jews were killed in 1939, but open mass killings subsided until June of 1941.