During this time, a series of massive wars took place in western China, including the Kumul Rebellion, the Sino-Tibetan War and the Soviet invasion of Xinjiang. Although the central government was nominally in control of the entire country during this period, large areas of China remained under the semi-autonomous rule of local warlords, provincial military leaders or warlord coalitions. Nationalist rule was strongest in the eastern regions around the capital Nanjing, but regional militarists such as Feng Yuxiang and Yan Xishan retained considerable local authority. The Central Plains War in 1930, the Japanese aggression in 1931 and the Red Army's Long March in 1934 led to more power for the central government, but there continued to be foot-dragging and even outright defiance, as in the Fujian Rebellion of 1933–34.