The early history of the Karen remains problematic, and there are various theories regarding their migrations. It appears that Karen peoples originated in the north, possibly in the high plains of Central Asia, and emigrated in stages through China into Southeast Asia, probably after the Mon but before the Burmese, Thai, and Shan reached what is now Myanmar and Thailand. Their slash-and-burn agricultural economy is an indication of their original adaptation to hill life. Eighth-century A.D. inscriptions mention the Cakraw in central Burma, who have been linked with the modern Sgaw. There is a thirteenth-century inscription near Pagan bearing the word "Karyan," which may refer to Karen. Seventeenth-Century Thai sources mention the Kariang, but their identity is unclear. By the eighteenth century, Karen-speaking people were living primarily in the hills of the southern Shan states and in eastern Burma. They developed a system of relations with the neighboring Buddhist civilizations of the Shan, Burmese, and Mon, all of whom subjugated the Karen. European missionaries and travelers wrote of contact with Karen in the eighteenth century. During the turmoil among the Burman, Yuan, and Siamese kingdoms in the second half of the eighteenth century, the Karen, whose villages lay along the armies' routes, emerged as a significant group. Many Karen settled in the lowlands, and their increased contact with the dominant Burman and Siamese led to a sense of oppression at the hands of these powerful rulers. Groups of Karen made numerous mostly unsuccessful attempts to gain autonomy, either through millennarian syncretic religious movements or politically. The Red Karen, or Kayah, established three chieftainships that survived from the early nineteenth century to the end of British rule. In Thailand Karen lords ruled three small semifeudal domains from the mid-nineteenth century until about 1910. British and American Christian missionaries arrived in Burma after the British annexation of lower Burma in 1826. The Karen, many of whom had converted to Christianity, had a distinctive though ambiguous relationship with the British, based on shared religious and political interests; prior to World War II they were given special representation in the Burmese Legislative Assembly. Christian missionary activity may have been the most important factor in the emergence of Karen nationalism, through the development of schools, a Karen literate tradition, and ultimately an educated Karen elite whose members rose in the ranks of the British colonial service. In 1928 the Karen leader, Dr. Sir San C. Po, argued for an autonomous Karen state within a federation. During the war, the Karen remained loyal to the British after the Japanese occupation; there was increased antipathy between the Karen and Burmans, who were backed by the Japanese. After the war, the British prepared for Burma's independence. The Karen National Union (KNU) promoted Karen autonomy, but after Aung San's assassination in 1947 hopes for an independent Karen state were shattered. Since Burmese independence in 1948, the Karen relationship with Burma has been primarily political. The old Karen-ni states formed Kayah State, and in 1952 the Burmese government established Karen State with Pa-an as its capital. During the 1964 peace negotiations, the name was changed to the traditional Kawthoolei, but under the 1974 constitution the official name reverted to Karen State. Many Karen, especially those in the lowland deltas, have assimilated into Burmese Buddhist society. In the hill regions many resist Burmese influence and some support, directly or tacitly, the insurgent KNU movement, which has been at war since 1949, in its efforts to achieve independence from Burmese rule. It is currently in a coalition with other ethnie groups and Aung San Suu Kyi's party, the National League for Democracy, which supports the formation of a union of federal states. The Kawthoolei (the name for the KNU territory) government has the difficult task of interacting with the Karen revolutionary military hierarchy and with the heterogeneous Karen population, which consists of both nonhierarchical traditional hill Karen and more educated delta Christian Karen who have joined them. Movement back and forth across the Thai-Myanmar border continues as Karen villagers cross to cut swiddens and Karen political refugees arrive in increasing numbers in Thailand's Mae Hon Son Province. In Thailand the Karen are facing assimilation into Thai society through mass education, the economic necessity of engaging in wage labor for Thai employers, and the assimilation of highland Karen into a generalized "hill tribe" category generated by Thai and foreign tourists.