Nearly 300,000 Polish Jews fled to Soviet-occupied Poland and the interior of the Soviet Union between the start of the war in September 1939 and the German invasion of the Soviet Union in June 1941. After the German invasion of the Soviet Union, more than a million Soviet Jews fled eastward into the interior. The Soviet authorities imprisoned many refugees and deportees in the Gulag system in the Urals, Soviet Central Asia or Siberia, where they endured forced labor, extreme conditions, hunger and disease. Nonetheless, most managed to survive, despite the harsh circumstances.