approximately one-third of the male population were monks. By the beginning of the 20th century, about 750 monasteries were functioning in Mongolia. The Stalinist purges in Mongolia that began in 1937 affected the Republic by killing more than 30,000 people. Japanese imperialism became even more alarming after the invasion of neighboring Manchuria in 1931. During the Soviet-Japanese Border War of 1939, the Soviet Union successfully defended Mongolia against Japanese expansionism.
In August 1945 Mongolian forces also took part in the Soviet Manchurian Strategic Offensive Operation in Inner Mongolia. The Soviet threat of seizing parts of Inner Mongolia induced China to recognize Outer Mongolia's independence, provided that a referendum be held. The referendum took place on October 20, 1945, with (according to official numbers) 100% of the electorate voting for independence. After the establishment of the People's Republic of China, both countries confirmed their mutual recognition on October 6, 1949.
On January 26, 1952, Yumjaagiin Tsedenbal took power. In 1956 and again in 1962, Choibalsan's personality cult was condemned at the ruling Mongolian People's Revolutionary Party Central Committee plenums. Mongolia continued to align itself closely with the Soviet Union, especially after the Sino-Soviet split of the late 1950s. In the 1980s, an estimated 55,000 Soviet troops were based in Mongolia. While Tsedenbal was visiting Moscow in August 1984, his severe illness prompted the parliament to announce his retirement and replace him with Jambyn Batmönkh.
The introduction of perestroika and glasnost in the USSR by Mikhail Gorbachev strongly influenced Mongolian politics, leading to the peaceful Democratic Revolution and the introduction of a multi-party system and market economy. A new constitution was introduced in 1992, and the "People's Republic" was dropped from the country's name. The transition to market economy was often rocky. The early 1990s
