<P> The Beiyang government in north China joined the Allied intervention in the Russian Civil War, sending forces to Siberia and North Russia beginning in 1918 . </P> <P> Mongolia and Tuva became contested territories . After being occupied by the Chinese General Xu Shuzheng in 1919, they came under the sway of the Russian White Guard General turned independent warlord, Ungern von Sternberg in 1920 . Soviet troops, with support from Mongolian guerrillas led by Damdin Sükhbaatar, defeated the White warlord and established a new pro-Soviet Mongolian client state, which by 1924 became the Mongolian People's Republic . </P> <P> In 1921 the Soviet Union began supporting the Kuomintang (KMT), and in 1923 the Comintern instructed the Chinese Communist Party (commonly abbreviated as CCP) to sign a military treaty with the KMT . On May 31, 1924, the two governments signed an agreement to establish diplomatic relations, while the Soviet government renounced in that agreement all privileges granted to the Tsarist government in China . But in 1926 KMT leader Chiang Kai - shek abruptly dismissed his Soviet advisers and imposed restrictions on CCP participation in the government . By 1927, after the conclusion of the Northern Expedition, Chiang purged the CCP from the KMT - CCP alliance, resulting in the Chinese Civil War which would last until 1949, a few months after the proclamation of the People's Republic of China, led by Mao Zedong . During the war the Soviets gave some support to the CCP, which in 1934 suffered a crushing blow when the KMT brought an end to the Chinese Soviet Republic, thus causing the CCP's Long March from Shaanxi . The Soviet Union tried and failed in an attempt to make the Hui hostile to China . </P> <P> The Sino - Soviet conflict of 1929 was a minor armed conflict between the Soviet Union and the Republic of China over the Manchurian Chinese Eastern Railway . The Chinese seized the Manchurian Chinese Eastern Railway in 1929, swift Soviet military intervention quickly put an end to the crisis and forced the Chinese to accept restoration of joint Soviet - Chinese administration of the railway . </P>

Who did the soviet union support in china civil war