The largest number of non-Tai peoples were the Chinese. In 1987 an estimated 11 percent of the total Thai population, or about 6 million people, were of Chinese origin, which meant that Thailand had the largest Chinese population in Southeast Asia. Assimilation of the various Chinese communities was a continuing process. Chinese were encouraged to become Thai citizens, and in 1970 it was estimated that more than 90 percent of the Chinese born in Thailand had done so. When diplomatic relations were established with China in the 1970s, resident Chinese not born in Thailand had the option of becoming Thai citizens; the remaining permanent Chinese alien population was estimated at fewer than 200,000.
Given their historic role as middlemen, Chinese were found everywhere in Thailand, particularly in the towns. There was, however, a major concentration in the Bangkok metropolitan area and another in the central part of peninsular Thailand, where many Chinese were engaged in several capacities in the tin mines and on the rubber plantations. Although many Chinese played an important part in the ownership and management of economic enterprises and in the professions, a substantial portion had less lucrative and significant occupations (see National and Urban Structures: Class and Status , this ch.).
Except for a minority, the Chinese not only were Thai nationals but also had, in some respects at least, assimilated into Thai society; many spoke Thai as well as they spoke Chinese. Most of the descendants of pretwentieth-century immigrants and those people of mixed Chinese-Thai ancestry (the so-called thailand/th_glos.asp#Sino"> Sino-Thai--see Glossary) were so fully integrated into Thai society that they were not included in the Chinese population estimates.
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.