Identification. The Dai (one of China's fifty-five ethnic minorities) are valley-dwelling rice cultivators of China's southwest frontier. The name "Dai" has been used officially since 1953 to replace "Tai" or "Thai." There are three major subgroups: Dailü (who used to be called "Shui Baiyi" and "Shui Dai" by the Han, meaning "the Baiyi or Dai living near the water"); Daina (Han Baiyi or Han Dai, Chinese Baiyi or Dai); and Daija (Huayao Dai, "the Dai wearing bright-colored blouses"). Within each subgroup there are regional units such as Daide, Daipeng, Daila, Dailian, and Pudai. Neighboring groups—Lahu, Hani, Jingpo, Benglong, Wa, Bulang, and Achang—call the Dai "Bitso," "Siam," or "La Sam."
Location. The Dai live exclusively in Yunnan Province, mostly along the Yunnan-Myanmar (Burma) border. Over 55 percent of the population lives in the Dehong Dai and Jingpo Autonomous Prefecture (21°10′ to 23°40′ N and 99°55′ to 101°50′ E) and the Xishuangbanna Dai Autonomous Prefecture (23°50′ to 25°20′ N and 97°31′ to 98°43′ E); about 7 percent live in the border areas of the Lincang Prefecture. The rest are spread throughout south and southwestern Yunnan, with a very small number living in the north of the province. Most of the Dai regions are river valleys and pocket flatlands between the mountains covered with tropical or semitropical monsoon forests. With very few exceptions the people live at elevations of 500 to 1,200 meters above sea level. With the tropical and semitropical climate, the average rainfall is between 101 and 170 centimeters, the average annual temperature is 19° C, and the annual frost-free period is about 300 days. Each year in these regions is usually divided into two seasons, a dry season from November to May and a wet season from May to October, the latter receives most of a year's precipitation.
Demography. In 1990 the Dai population was 1,025,128. The Dailü and Daina are the major groups, making up 56 percent and 40 percent respectively of the total Dai population. The Daina, Daide, and Daipeng mainly live in Dehong and Lincang; the Dailü live mostly in Xishuangbanna, while the Daija are distributed in Yuanjiang and Xinping counties and the Red River valley. The Dai also have kin known as "Shan," "Tai," or "Thai" in Myanmar, Thailand, Laos, and Vietnam.
Linguistic Affiliation. Chinese scholars commonly hold that the Dai language with its dialects is a Subbranch of the Zhuang-Dong (Kam-Tai) Branch of the Sino-Tibetan Family. Some Western linguists classify it in the Thai-Austronesian Language Family. Five Dai written languages were in use before 1949: Dailü, Daina Daipeng, Jinping Dai, and Xinping Dai scripts. Those based on ancient Pali, Dailü, and Daina scripts were more popular and later formed the basis of present-day Xishuangbanna Dai and Dehong Dai writing.