The Holocaust saw the ghettoization, robbery, deportation and mass murder of Jews, alongside other groups under similar racial pretexts in occupied Poland by the 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). All Poles, Christian or Jewish, were bound for total annihilation. 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. The Soviet Union deported many Jews to the Soviet interior, where most survived the war. In 1941, Germany invaded the Soviet Union and began the systematic murder of Jews. 1.8 million Jews were killed in Operation Reinhard, shot in roundups in ghettos, died during the train journey, or killed by poison gas in the extermination camps. In 1943 and 1944, the remaining labor camps and ghettos were liquidated. Many Jews tried to escape, but surviving in hiding was very difficult due to factors such as the lack of money to pay helpers and the risk of denunciation. Only 1 to 2 percent of Polish Jews in German-occupied territory survived. After the war, survivors faced difficulties in regaining their property and rebuilding their lives. Especially after the Kielce pogrom, many fled to displaced persons camps in Allied-occupied Germany.