The Vorkuta Gulag was established by Soviet authorities in 1932, on a site in the basin of the Pechora River, located within the Komi ASSR of the Russian SFSR (present-day Komi Republic, Russia), approximately from Moscow and above the Arctic Circle. The city of Vorkuta was established to support the camp, which was constructed to exploit the resources of the Pechora Coal Basin, the second largest coal basin in the Soviet Union. There were approximately 132 sub-camps in the Vorkuta Gulag system during the height of its use in the Soviet prison system. From 1939, Polish prisoners were held at Vorkuta following the Occupation of Poland until the German invasion of the Soviet Union in 1941. Vorkuta was then also used to hold German prisoners of war captured on the Eastern Front in World War II as well as criminals, Soviet citizens and those from Soviet-allied countries deemed to be dissidents and enemies of the state during the Soviet era.