The Miao were first recorded in Chinese annals as a rebellious people banished from the central plains around 2500 B.C. by the legendary Yellow Emperor (Huang Di) of China. Because the Hmong today retain traces in their culture of the earliest known forms of Chinese social organization, some specialists have considered them the aboriginal inhabitants of China, predating the Han. Their legends, however, have led others to speculate that they may have originated from a northern polar region. Records exist of the Miao in China from 1300 to 200 B.C. ; from then until A.D. 1200 they were subsumed under the generic Chinese term for southern barbarians (Man). There are, however, good records of the Miao from 1200 to the present, and we can be fairly certain that they refer to the ancestors of the Hmong. Most focus on the many uprisings of the Miao against the Chinese state, bearing witness to a long historical displacement of the Hmong and other southern Chinese minority people from the centers of power as the Han Chinese population slowly expanded southward. Hmong began migrating into Southeast Asia around 1800. The last major Miao rebellions in China were in 1856.
In Vietnam and Laos, the Hmong fell under the authority of the French colonial government. A major Hmong rebellion against excessive levies on opium production broke out in Laos in 1919; it took the authorities several years to suppress the revolt, which assured the Hmong of a measure of self-representation. During the Indochina wars, Hmong loyalties were severely fragmented among the royalists, neutralists, and opposition in Laos, and large numbers fled to Thailand when the Pathet Lao gained control of their country in 1975. In Thailand a similar polarization occurred as a result of the 1959 ban on opium production; the ban failed to suppress opium production, giving rise to a government policy of tolerating an illegal practice. Many Hmong supported the armed rural struggle of the Communist Party of Thailand against the government in the 1960s and early 1970s, which has now largely ended. Policies of tolerance toward opium production have also now ended, and this may facilitate Hmong acceptance of the many programs targeted at replacing opium-poppy cultivation with alternative cash crops.