Tai tribes, linked by language and culture, migrated to Southeast Asia from what is now southwestern China in the first century c.e. to escape domination by the Chinese empire.

Today, various Tai peoples, also referred to as Dai, Siamese, Thai, and Lao, are settled over large areas of southwest China and Southeast Asia. They are linked by similarities of language as well as diet, architecture, and agricultural practices. The Yunnanese of southern China share many ethnic and cultural traits with the Tais to the south of China, while the other groups of people speaking dialects of Tai can be found within a few hundred miles of Guangzhou (Canton), in southern China.

Excavations suggest that Tai people lived in southwestern China as early as 1450 b.c.e., before ethnically Chinese people arrived in the area. However, the original location of the Tais remains uncertain. Theories place them in them in the Yangtze River Valley before the arrival of the Chinese, or in northern Laos or Vietnam, between the Song Hong and Song Da (Red and Black Rivers). The uncertainty comes in part from the wide dispersal of people speaking Tai languages and the Tais’ long-standing tradition of absorbing elements from other cultures. Although a precise understanding of the movements of Tai peoples into Southeast Asia remains unknown and perhaps unknowable as a result of conflicting evidence from linguistic, archaeological, and historical sources, the fact remains that Tai people are today distributed over large areas in Southeast Asia and southern China.

Most probably, the Tai migration into Southeast Asia began as related groups of people, speaking a tonal language related to, yet distinct from, that of most Chinese, moved into Southeast Asia from southwestern China in several waves, beginning around 2,500 b.c.e. and continuing until as recently as the sixteenth century c.e. Southeast Asia had been inhabited by Malay peoples since before the Neolithic revolution. Malays had already been pushed south or absorbed by earlier invaders, mostly Mon and Khmer (Cambodian), from the north. The Khmer politically and ethnically dominated the region but were unable to halt the stream of Tais into the region. An early appearance of the Tai in the historical record comes from the first century c.e. In 78 c.e., a Tai prince known as Lei Lao, whose predecessor had earlier submitted to the Chinese Han emperors, rebelled against Chinese rule. The subsequent military losses of the Tai to the Chinese led to a large migration of Tais from the Yangtze River Valley onto the Shan Plateau of what is now Myanmar (Burma). This account represents only a small portion of a long-term movement of Tai peoples to the south but was one of the first large-scale migrations. A more profound movement of Tais came a few centuries later, as population pressures from the Chinese pushed the Tais southward.

From roughly the sixth century through the sixteenth century, a slow and steady movement occurred of Tais into Southeast Asia, out of the reaches of the Chinese emperors. They quickly dominated or drove out local peoples and began a process of adaption and assimilation into local environments. Many of the earlier inhabitants of the area, especially the Khmers, had been heavily influenced by Indian culture, which would later have a great impact on the Tai as they began to dominate the area. Tais became predominantly Theravāda Buddhists and adopted an Indian-based writing system and much of the Hindu conception of the world. However, Tais who remained geographically closer to China, such as those in the highlands of Vietnam and in southern China, remained more Chinese in their culture. By the early eleventh century, the Tais had established kingdoms in the northern reaches of the Chao Phraya River Valley. They then built a line of cities farther down the valley, culminating in the founding of Bangkok (Krung Thep) in the late eighteenth century near the mouth of the Chao Phraya River. The Tai continued to conquer and absorb Malay peoples farther south while confining the Khmers to a rump state of their former empire.

The movement of Tai peoples into Southeast Asia had profound impacts on the region and on the Tais themselves. Intermarriage between invading Tais and indigenous Malays and other earlier inhabitants seems to have occurred on a limited basis, with the Tai culturally and politically dominating large areas of the region. The movement of the Tai down the Chao Phraya Valley ended the domination of the Khmers over much of the region and reduced the once powerful Khmer Empire to the status of a vassal state of Siam until the French Empire absorbed Cambodia in the late nineteenth century. The strength of various Tai states in the Chao Phraya Valley prevented the Burmese from expanding to the east and created uncertainty over the docility of Tais of the Shan Plateau. The absorption by Tais of indigenous cultures, along with borrowing from Indian culture, most heavily through Buddhism, created the modern Thai cultural identity. The Thai dominated Siam (called Thailand since 1936) and Laos, while other Tai peoples ethnically dominated parts of southern China, Myanmar, and Vietnam.

• Bellwood, P. Prehistory of the Indo-Malaysian Archipelago. New York: Academic Press, 1985. Although focused more on the area south of the main thrust of the Tai into Southeast Asia, it is useful for showing the impact of the arrival of the Tai on other peoples in the region.
• Heidhues, Mary Somers. Southeast Asia: A Concise History. New York: Thames and Hudson, 2000. This is a good introduction to the history of the region from prehistory to the present. Bibliography and index.
• Higham, C. The Archaeology of Mainland Southeast Asia. New York: Cambridge University Press, 1989. Higham presents archaeological evidence that occasionally disputes more traditional historical records of the area. Bibliography and index.
• Jumsai, Manich. Popular History of Thailand. 5th ed. Bangkok: Chalermnit, 2000. Written by a Thai scholar for the Western reader.
• Wood, W. A. R. A History of Siam. Bangkok: Wachrin, 1994. Useful for its inclusion of several differing theories of the geographic origins of the Tai people. Wood focuses mostly on turns of government and wars. Tables and indexes.