Immigration to Thailand, except for the Chinese, has traditionally been comparatively small. The decade of the 1920s was a period of large-scale Chinese immigration of 70,000 to 140,000 a year. Strict immigration regulations have all but stopped the legal flow of Chinese into the country, but during the Franco-Indochinese war some 45,000 Vietnamese refugees settled in Thailand. An immigration quota, introduced in 1947, now limits migration from any one country to 100 persons annually.
As of December 1992, the UN estimated that 63,600 refugees were living in Thailand; these represented part of the flood of over 4 million refugees who had left Cambodia, Laos, and Vietnam since the 1970s. Some 370,000 Cambodians on the Thai–Cambodian border were repatriated during 1992–93. The 36,000 Cambodian refugees who fled their country after the political and military events of 1997 were repatriated by 1999, and three border camps were subsequently closed. In 1986, the Thai government began forcibly repatriating many refugees from Laos. The last refugee camp for Vietnamese was closed in February 1997.
In June 1998, the Thai government formally requested increased UNHCR assistance for some 100,000 Karen and Karenni refugees living in 11 camps in Thailand along the Myanmar border. A comprehensive registration of the border population was completed through the joint efforts of the Thai government and UNHCR in 1999. UNHCR is also working with the government to establish uniform criteria for accepting new arrivals from Myanmar, as it is unlikely that repatriation will be possible in the near future.
The net migration rate in 2000 was -0.01 migrants per 1,000 population.