Along with Westerners, the Chinese merchant class dominated the economy in the nineteenth century, especially with the exportation of rice. In the early twentieth century, the Chinese established their own educational institutions, resulting in antipathy toward them under the nationalistic Phibun regime, which blamed the Chinese for the country's economic problems. In 1938, the Phibun government taxed the Chinese, limited the use of their language in schools, and closed most Chinese-language newspapers. Chinese immigration came to a virtual halt. While anti-Chinese sentiment remained strong, by the 1970s virtually all the Chinese had Thai citizenship. With the growth of a more open and democratic society in the 1990s, the Chinese began to express their culture openly.
Since it came under Thai control in 1786, the Malay Muslim population has posed difficulties for the Thai state. This region has mounted numerous rebellions against central authority over the past two centuries. In 1948, the Phibun regime banned Malay and Islamic organizations, sparking a rebellion that was violently crushed. Education has been a point of conflict between Thai authorities and the Malay Muslims since the government introduced compulsory education in 1921. As a result, many Muslims sent their children to Malaysia and other Muslim countries to be educated. In the 1960s, returning students joined various independence movements. Guerrilla activities in the south reached their height between 1970 and 1975. Counterinsurgency operations failed to end support for the separatists. In the late 1980s, the national political environment changed with greater sensitivity to the Muslim religion and culture. The civilian government elected in 1992 initiated reforms to ease tension in the Muslim south.
The Thai government treats the Khmer as part of a generic northeastern Thai ethnic category called Isan. Efforts to assimilate the Khmer into the national culture in the 1960s and 1970s were spurred by concern over their support for communist insurgents in the northeast. In the 1990s there was a cultural revival among the Khmer in the northeast that included the formation of dance and music groups to promote Khmer culture. The hill tribes in the north, with the exception of the Lawa and Karen, are relatively recent immigrants. The majority of hill tribe members did not become citizens until recently and lacked political rights. These hill tribes have faced economic difficulties related to their lack of land rights. The authorities generally have viewed them as primitive peoples. In the 1980s and 1990s, there was encroachment on their land by lowlanders, who believed that their presence was a key factor in environmental degradation in highland areas. Proponents of rights for the tribes in the 1990s led to the granting of citizenship for the hill tribes. Nevertheless, there are many conflicts, including those involving corrupt government officials and business interests that are attempting to exploit highland resources.