The Warlord Era (1916–1928) was a period in the history of the Republic of China when the country was divided among military cliques in the mainland regions of Sichuan, Shanxi, Qinghai, Ningxia, Guangdong, Guangxi, Gansu, Yunnan and Xinjiang. The era lasted from the death of Yuan Shikai in 1916 until 1928, when the conclusion of the Northern Expedition with the Northeast Flag Replacement began the "Nanjing decade"; however, when old warlords, such as Wu Peifu and Sun Chuanfang, were deposed, new minor warlords persisted into the 1930s and 1940s, as the central government struggled to keep its allies under rein, a great problem for the Kuomintang (KMT) through World War II and after the civil war. Some of the most notable warlord wars, post-1928, including the Central Plains War, involved nearly a million soldiers. The division of the country continued after the Warlord Era until the fall of the Nationalist government at the end of the Chinese Civil War.