Jewish ghettos in German-occupied Poland were established during World War II in hundreds of locations across occupied Poland. Most Jewish ghettos had been created by Nazi Germany between October 1939 and July 1942 in order to confine and segregate Poland's Jewish population of about 3.5 million for the purpose of persecution, terror, and exploitation. In smaller towns, ghettos often served as staging points for Jewish and mass deportation actions, while in the urban centers they resembled walled-off prison-islands described by some historians as little more than instruments of "slow, passive murder," with dead bodies littering the streets.