People speaking Tai languages constitute by far the dominant linguistic group in the country. The largest group of Tai speakers are the Thai, who constitute more than half the population. The
Thai live in almost all areas of the country and speak related dialects that are differentiated by accents and a few words. The most common dialect is called standard Thai (Siamese), with the greatest concentration of speakers in the Chao Phraya delta. Since standard Thai is the national language, which is used in all schools and official publications and by the national press and broadcast media, most Tai speakers can communicate adequately among themselves.
Tai-speaking peoples are found not only in Thailand but also in Myanmar, Laos, Vietnam, and southern China. Little difference exists among the Tai speakers in Laos, Myanmar, China, and northern Thailand, but there is a noticeable difference between these peoples and the Thai living in the Central Plain and close to Cambodia. Speakers of Lao are the largest linguistic minority in Thailand; they live in the Khorat Plateau adjacent to Laos and constitute about one-fourth of Thailand's population.
Wars pitting Thailand against Myanmar and Cambodia in the past brought many refugees and prisoners of war into Thailand. The Mon, a people of Myanmar, settled in many parts of the north, centre, and west, although they are now concentrated in an area just west of Bangkok. The Khmer settled in the east along the Cambodian border. Both groups traditionally spoke languages of the Mon-Khmer group of the Austro-Asiatic family; most of these people, however, now use standard Thai, many speaking it as a first language.
Among speakers from the other two language families, Malays at the southern tip of peninsular Thailand are the most numerous. The Karen and other speakers of Sino-Tibetan languages sparsely inhabit the western and northern mountains. Except for the Karen, who mixed rather easily with the northern Thai, the hill tribes prefer to keep themselves isolated. They occasionally come down to the markets to trade with the lowlanders. Two small hill tribes, the Lawa (or Wa) and Semang, are of special interest. The Lawa, who speak a Mon-Khmer language, are believed by some historians to be the original dwellers of the delta plain, who subsequently were driven into the hills of the northwest by the Tai speakers who conquered the area. The Semang of the southern mountains speak a dialect of Malay and live by hunting with blowpipes and spears.
The Chinese constitute a significant minority in Thailand. In the commercial centres of Bangkok and other cities, people of Chinese descent operate both large and small commercial enterprises. The Chinese also make a living as middlemen and storekeepers. Most of them speak Chinese, although many also speak standard Thai.
English is also widely used in Thailand, especially in the urban centres. English is a required subject in secondary schools and the universities, and frequent contact with English-speaking foreigners also encourages the use of English. The prevalence of various South Asian dialects reflects the large number of Indian merchants and their descendants in the commercial centres.