With the establishment of the People's Republic of China in 1949, American immigration policy towards Chinese emigrants and the highly controversial subject of foreign policy with regard to the PRC became invariably connected. The United States government was presented with the dilemma of what to do with two separate "Chinas". Both the People's Republic of China and the Republic of China wanted be seen as the legitimate government and both parties believed that immigration would assist them in doing so.
During the 1940s and 1950s, the United States, the Republic of China, and eventually the PRC consistently used the movement of people, their laws controlling their borders, citizen services, and their interactions with the Chinese diaspora to promote the legitimacy and positive image of their respective governments internationally. Overseas Chinese were seen as extremely pertinent to either side claiming legitimacy, as both the Republic of China and the People's Republic of China realized the political and social clout held by those overseas Chinese Americans.
Furthermore, the United States also realized that it had to be very careful in choosing the right policies with regard to the status of Chinese immigrants. On the one hand the United States had to come to terms with the fact that mainland China was "lost" to Communism and on the other it had to ensure its interests in Taiwan were not compromised. US immigration policy for the next thirty years was implemented with a notion of duality. The United States government would open its doors to Chinese immigrants from both sides of the strait, however; American public opinion was not so welcoming (see Chinese American history).
In October 1949, the People's Republic of China was established after a bitter and long civil war that had lasted nearly twenty years. The Communists led by Mao Zedong had forced the Guomindang who had originally ruled China under the Republic of China to retreat to the island of Taiwan, which in effect created two separate "Chinas". The newly established People's Republic of China began constructing its foreign policy dealings with other countries as a way of legitimizing its rule. The first of its dealings was with the Soviets. The Soviet Union recognized the People's Republic on October 2, 1949. Earlier in the year, Mao had proclaimed his policy of "leaning to one side" as a commitment to the socialist bloc. In February 1950, after months of hard bargaining, China and the Soviet Union signed the Treaty of Friendship, Alliance, and Mutual Assistance, valid until 1980.