Another historically significant example of forced labour was that of political prisoners, people from conquered or occupied countries, members of persecuted minorities, and prisoners of war, especially during the 20th century. The best-known example of this are the concentration camp system run by Nazi Germany in Europe during World War II, the "Gulag" camps run by the Soviet Union, and the forced labour used by the military of the Empire of Japan, especially during the Pacific War (such as the Burma Railway). Roughly 4,000,000 German POWs were used as "reparations labour" by the Allies for several years after the German surrender; this was permitted under the Third Geneva Convention provided they were accorded proper treatment. China's ("labour reform") system and North Korea's camps are current examples.