In 1924, after the death of the religious leader and king Bogd Khan,
a Mongolian People's Republic was proclaimed with support from the Soviet Union.
In 1928, Khorloogiin Choibalsan rose to power. He instituted collectivisation of livestock,
the destruction of Buddhist monasteries and the Mongolia's enemies of the people persecution resulting in the murder of monks and other people. In Mongolia during the 1920s, approximately one third of the male population were monks. By the beginning of the 20th century about 750 monasteries were functioning in Mongolia.[12] The Stalinist purges in Mongolia beginning in 1937, affected the Republic as it left more than 30,000 people dead. 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[citation needed] induced China to recognize Outer Mongolia's independence, provided that a referendum was 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.
In January 26, 1952, Yumjaagiin Tsedenbal took power. In 1956 and again in 1962, Choibalsan's personality cult was condemned. Mongolia continued to align itself closely with the Soviet Union, especially after the Sino-Soviet split of the late 1950s. While Tsedenbal was visiting Moscow in August 1984, his severe illness prompted the parliament to announce his retirement