China was divided and devastated by wars in the 1920s–1940s. Guomindang (GMD, the Nationalist Party) and the Chinese Communist Party (CCP) formed a United Front to fight against the warlords in 1924. After they won great victories in the Northern Expedition, Jiang Jieshi (Chiang Kai-shek) turned the guns on the Communists in a political betrayal, just before he formed the Nationalist government in Nanjing to replace the warlord-supported government in Beijing (Beiyang government) in 1927. The CCP, after surviving the bloody setback, re-grouped in the rural mountains in southeast China of Jiangxi and Fujian to start all over again. The Nationalist government, however, faced both domestic and foreign challenges in the effort to create a unified modern sovereign state of China. On one hand, it continued the negotiations with foreign powers that had been carried on by the Beiyang government to recover the sovereign rights that China had lost through the unequal treaties. Those rights included sovereignty over customs and quarantine services, tariffs, medical regulations, and education. On the other hand, the Nationalist government attempted to eliminate the CCP, its political rival, by launching major military campaigns against the Communist bases in the Jiangxi and Fujian border regions. The Communists, against all odds, survived the attacks and completed the Long March in 1934–1935 to resettle in Yanan (Yan’an, Yenan, 延安) in north central China, where they continued the revolution. When the Nationalists were fighting the Communists, Japanese military forces in northeast China (Manchuria) orchestrated the aggressions in 1931 to expand their territory in China, and then launched the full-scale invasion in 1937, starting World War II. In this national crisis, patriotic Chinese called to unite against the Japanese invaders, leading to the formation of a Second United Front of the GMD and the CCP in 1937. China’s war against Japanese invasion, which became part of World War II, did not end until the Allies’ victory over Japan. Against this background of wars and political upheavals, health modernizers of the Nationalist government made substantial efforts in creating an institutional system of modern national health, with significant assistance of the League of Nations and the Rockefeller Foundation. The Communists, in the meantime, managed to create health 155programs in rural areas with limited resources but relied on local people and used both Chinese and Western medicines. International medical aid from the anti-fascist movement helped improve the standards of the CCP’s medical services and influenced the health development in CCP regions.