Chinese migration to Thailand can be traced to the 13th century, according to the Minority Rights Group. Trade between Siam and China existed from an early period. Rhinoceros horn, kingfisher feathers and ivory were among the items sought by the Chinese. The famous 15th-century explorer-eunuch, Zheng Ho, commented that when he arrived in Siam there were many Chinese who lived there because the women were easy to get. He also commented on the large number of monks and the fact that women seem to run everything. Among the early places where Chinese went to work was the Ayutthaya Kingdom (1351 to 1767) in Thailand.

By the time the Europeans arrived in what is now Thailand, Thai harbors were filled Chinese junks and Thai ports were home to Chinese that spoke a number of dialects. Siam was a major destination for Chinese exports and was a major transshipment center for goods to other places and islands in Asia and Oceania. Bangkok was a Chinese trading post before it was an important Thai city. King Ram I was married to the daughter of a rich Chinese merchant.

By the 19th century, the Chinese were an important segment of Thai society. They ran much of the economy and controlled trade and in many ways were Thailand’s window to the outside world. In both Thailand and China their money help strengthen the economy and finance the construction of many temples and buildings. Many of the hardworking and enterprising Chinese in Malaysia, Singapore, Indonesia, Thailand and Vietnam are from the southern Chinese province of Fujian. In Thailand many are also from Chaozhou area of Guangdong Province.

Westerners and Chinese merchant class dominated the economy in the nineteenth century, especially with the exportation of rice. The accommodation between Thai and Chinese historically depended in part on the changing economic and political interests and perspectives of the Thai monarchs and others in the ruling group. Also relevant were the roles assigned to the Chinese at various times, e.g., in the nineteenth century, that of tax farmers. Under the tax farming system, private individuals were sold the right to collect taxes at a price below the actual value of the taxes. The barriers between Thai and Chinese became more rigid in the early twentieth century with the emergence of Thai and Chinese nationalism and also the increased tendency of Chinese females to accompany male immigrants, which reduced the amount of intermarriage. Consequently, despite a level of Chinese integration in the host society surpassing that found elsewhere in Southeast Asia, the Chinese remained a separate ethnic community, although the boundaries became less defined in the more mobile post-World War II society. The Chinese spoke a number of southern Chinese dialects, the most important being Teochiu, which was used by most Chinese as a commercial lingua franca.

The number of Chinese in Thailand more than doubled in the 19th century. By 1910 nearly 10 percent of Thailand’s population was Chinese. Whereas earlier immigrants had intermarried with the Thai, the new arrivals frequently came with families and resisted assimilation into Thai society. Chinese nationalism, encouraged by Sun Yat-sen, the leader of the Chinese revolution, had also begun to develop, parallel with Thai nationalism. The Chinese community even supported a separate school system for its children. Legislation in 1909 requiring adoption of surnames was in large part directed against the Chinese community, whose members would be faced with the choice of forsaking their Chinese identity or accepting the status of foreigners. Many of them made the accommodation and opted to become Thai–if in name only. Those who did not became even more alienated from the rest of Thai society.