due to the existence of numerous jurisdictions, criminals could commit a crime in one jurisdiction and then easily escape to another. This became a major problem during the Republican period, with the rise of post–Imperial Warlord era and the collapse of central authority in the 1920s and the 1930s. Crime often flourished, especially organised crime by different warlord groups. The majority of concessions in Asia were treaty ports, port cities in China and Japan that were opened to foreign trade mainly by the unequal treaties forced upon them by Western powers, as well as cities in Korea opened up similarly by the Japanese Empire prior to its annexation of the Korean peninsula. The treaty port system in China lasted approximately one hundred years beginning with the 1841 Opium War. The system effectively ended when Japan took control of most of the ports in the late 1930s, The Russians relinquished their treaty rights in the wake of the Russian revolution in 1917, and the Germans were expelled in 1914. The three main treaty powers, the British, the Americans, and the French continued to hold their concessions and extraterritorial jurisdictions until the Second World War. This ended when the Japanese stormed into their concessions in late 1941. They formally relinquished their treaty rights in a new "equal treaties" agreement with Chiang Kai-shek's Nationalist Government in exile in Chongqing in 1943. The international communities that were residues of the treaty port era ended in the late 1940s when the communists took over and nearly all foreigners left. Within the concessions in China, the occupying foreign powers administered distinct legal systems. The two main courts judging extraterritorial cases were the Shanghai Mixed Court and the British Supreme Court for China. Similar courts were established for treaty countries, e.g. the United States Court for China. These had jurisdiction over the concession areas, which formally remained under Qing sovereignty. Initially, Chinese people who committed crimes in, say, the British zone, were remanded to Chinese authorities. Suez and Panama canals The Suez and Panama Canals were originally established as concessions administered by the foreign powers who funded their construction. Between 1859 and 1956, the British and French owned Suez Canal Company operated the Suez Canal while the United States government administered the area surrounding the Panama Canal from 1903 to 1999. Concessionary administration of the Suez Canal was ended when Egyptian President Gamal Abdel Nasser nationalised the