Like other countries of Southeast Asia, Thailand in prehistoric times was peopled through successive migrations from central Asia into territory already inhabited by the Negrito peoples. Although a few Thai groups (ethnically related to the Shan of Myanmar and the Lao of Laos) migrated to the northern hill country of Thailand, the main body of Thais remained in Yunnan, China, where by A.D. 650 they had organized the independent kingdom of Nanchao. By 1000, however, the Chinese had overrun Nanchao and made it a tributary state. With the destruction of the kingdom of Nanchao by the Mongols under Kublai Khan in 1253, the slow infiltration of Thailand from the north turned into a mass migration. By that time the Khmer Empire was well established in the Chao Phraya valley and on the Korat plateau.
The Thais captured the Khmer town of Sukhothai, in N central Thailand, and a new Thai nation, with its capital at Sukhothai, soon developed. During this period (c.1260–1350), King Rama Kamheng, whose 40-year reign began c.1275, borrowed from the Khmers of Cambodia the alphabet that the Thais still use. He extended Sukhothai power southward to the sea and down the Malay Peninsula, and contact was made with India. After the death of Rama Kamheng, Sukhothai declined and was absorbed by Rama Tibodi, prince of Utong, who established (c.1350) a new capital at Ayutthaya. The kings of Ayutthaya consolidated their power in S Siam and the Malay Peninsula, then launched a long series of indecisive wars against the Lao state of Chiang Mai and against Cambodia, which did not end until the 19th cent. The 16th cent. saw the beginnings of warfare with the Burmese; in 1568 the Burmese captured Ayutthaya and dominated the country until c.1583, when King Naresuan (1555–1605) drove them from Siam. He captured Tanintharyi and Dawei in S Myanmar and the major port of Myeik.
Siam's relations with the West commenced after 1511, when Portuguese traders and missionaries began to arrive. Adroit diplomacy, developed during this time, enabled Siam to remain independent of European colonization, the only country in Southeast Asia able to do so. In the early 17th cent. the Dutch and British broke Portugal's monopoly. Siam became, so far as Europe was concerned, the most consequential kingdom in Southeast Asia, and the brilliance of its court under King Narai (reigned 1657–88) was proverbial. The French, aided by the Greek adventurer Constantine Phaulkon, who had risen to power at the Siamese court, launched a bid for dominance in Siam that provoked an antiforeign coup (1688). Phaulkon was executed, and Siam was closed to most foreigners for over a century.
In 1767 the Burmese, after several attempts, finally destroyed Ayutthaya. Gen. Phya Tak, or Taksin, however, quickly rallied the Thai forces, and within a decade he drove (c.1777) the Burmese from the country and established his capital at Thon Buri. His successor, General Chakkri (reigned 1782–1809), later known as Rama I, moved the capital from Thon Buri across the river to Bangkok and founded the Chakkri dynasty, thereafter the ruling house of Siam. In the 19th cent. the authority of Bangkok was at last established over N Siam, and relations with the West were resumed; Siam signed commercial treaties with Great Britain (1826) and the United States (1833). The independence of the kingdom was threatened, however, when Great Britain extended its sway to Malaya and Burma, and France carved out an empire in Indochina.
By opening their posts to European trade, by bringing in Western advisers, by strengthening the central administration as against the hereditary provincial chieftains, and by playing off British against French interests, the Siamese managed to stay free. Even so, the establishment of Siam's boundaries meant the surrender of its claims to Laos (1893) and parts of Cambodia (1907) and of its suzerainty over Kedah, Perlis, Kelantan, and Terengganu (1909), on the Malay Peninsula. The Pattani sultanate (now Thailand's three southern provinces), however, was annexed in 1902. The Westernization of Siam took place under an absolute monarchy and was chiefly the work of Mongkut (reigned 1851–68), or Rama IV, and his son Chulalongkorn (reigned 1868–1910), or Rama V. Siam became a constitutional monarchy in 1932, when a bloodless coup forced Prajadhipok (reigned 1925–35), Rama VII, to grant a constitution.
The two young leaders of the coup, Pibul Songgram and Pridi Phanomyang, both educated in Europe and influenced by Western ideas, came to dominate Thai politics in the ensuing years. In 1934 the first general elections were held; a year later Prajadhipok abdicated, and a council of regency chose Ananda (reigned 1935–46) as Rama VIII. Pibul Songgram, a militarist, became premier in 1938. He changed the country's name to Thailand and instituted a program of expansion. Taking advantage of the initial French defeat (1940) in World War II, he renewed Thai claims in Cambodia and Laos. Japanese "mediation" resulted (1941) in territorial concessions to Thailand. In Dec., 1941, Pibul, despite the objections of Pridi Phanomyang, permitted the Japanese to enter Thailand, and in 1942 the government, under Japanese pressure, declared war on Great Britain and the United States.
With the help of the United States, Pridi formed a militant anti-Japanese underground. In 1943, Japan "granted" to Thailand territory in N Malaya and in the Shan states of Myanmar, but after the war Thailand was forced to return these territories and those acquired in 1941 to French and British control. Pridi Phanomyang became premier in the postwar government, while Pibul was briefly jailed as a war criminal. Pridi restored the name Siam as a repudiation of Pibul's policies. Inflation, corruption in government, and the mysterious death (1946) of King Ananda all contributed to the overthrow (1947) of Pridi's government by Pibul. Pridi fled the country and in 1954 appeared in Beijing as the professed leader of the Communist "Free Thai" movement, allegedly representing numerous Thais still in Yunnan, China.
Under Pibul's military dictatorship, the name Thailand was again adopted. Bhumibol Adulyadej, Rama IX, was crowned king in 1950 after a four-year regency. Thailand signed (1950) a technical and economic aid agreement with the United States and sent troops in support of the United Nations action in Korea. Thailand has received huge military grants from the United States and was the seat (1954–77) of the Southeast Asia Treaty Organization. The country, apprehensive over its proximity to China, remained consistently pro-Western in international outlook.
In 1957 a military coup led by Field Marshal Sarit Thanarat overthrew Pibul Songgram and made Gen. Thanom Kittikachorn premier. In 1958, however, with the stated purpose of combating Communism, Sarit deposed his own premier, suspended the constitution, and declared martial law. King Bhumibol Adulyadej proclaimed an interim constitution in 1959 and named Sarit premier. When Sarit died in 1963, Thanom Kittikachorn was returned to power. A new constitution was finally promulgated in 1968. Under Sarit and Thanom the country's economy in the 1960s continued to boom, spurred by a favorable export market and considerable U.S. aid. Thailand strongly supported the U.S. policy in South Vietnam, providing bases for U.S. troops and airfields for strikes against the North Vietnamese; thousands of Thai troops were sent in support of South Vietnam. The nation's foreign policy was closely geared to the U.S. presence in Southeast Asia and its economy became increasingly dependent upon U.S. military spending and subsidies. Thailand became one of the founding members of the Association of Southeast Asian Nations (ASEAN) in 1967.
Economic reversals came in 1970 when the international demand for rice dropped substantially (due in part to improved farming techniques in other countries) and the prices of tin and rubber fell; for the first time since 1933, Thailand suffered a trade deficit. In addition, the security of the country appeared threatened by the spread of the Vietnam War into Cambodia and Laos and by growing insurgencies, chiefly Communist led, in three separate areas within Thailand itself: in the south, where Malaysian Communists used Thailand as a staging base for operations in Malaysia and Thai Malay separatists mounted an insurgency that continued into the 1980s; in the north, where Communists trained in North Vietnam were believed to be organizing the hill peoples; and, most significantly, in the economically backward northeastern provinces, where a discontented minority had been active since the mid-1950s.
The increasing economic and security problems prompted a coup in Nov., 1971, by Premier Thanom Kittikachorn and three military aides, in which they abolished the constitution and the parliament and imposed military rule. Guerrilla raids against both Thai government forces and U.S. air bases continued. Economic conditions improved throughout 1972 as large numbers of U.S. military personnel were transferred from South Vietnam to bases in Thailand; by June of that year there were more U.S. forces in Thailand than in South Vietnam.
In Oct., 1973, the military regime of Thanom was toppled after a week of student demonstrations and violence in Bangkok. King Bhumibol Adulyadej appointed Sanya Thammasak as Thanom's successor, giving Thailand its first civilian premier in twenty years. The new premier promised to complete a constitution and to hold general elections. In May, 1974, citing the heavy burden of the office and the sharp criticism directed against the government, Sanya resigned, but he was soon persuaded to form a new government. In June he was sworn in as the head of a revamped, all-civilian cabinet. A new constitution was promulgated in Oct., 1974. Over the next few years the civilian government made little headway in establishing its authority. In 1976, the military took control of the government once again. After that, the military held power almost continuously until the early 1990s.
From the late 1970s, Thailand's political concerns were dominated by pressures resulting from warfare in Vietnam, Laos, and Cambodia and serious unrest in Myanmar (Burma); Thailand also experienced a massive influx of refugees from these countries. From 1975 onward, Thailand was a way station for Hmong refugees immigrating to the United States under its resettlement program. The Khmer Rouge used Thailand as a staging area after they were driven out of Cambodia by the Vietnamese, and internal fighting within the Cambodian government in 1997 sent a new flow of refugees into Thailand.
In 1992 there were signs of popular opposition to continued military rule and, after antigovernment demonstrators were killed, King Bhumibol Adulyadej appointed a civilian as interim prime minister. In the Sept., 1992, elections, parties opposed to the military won a majority, and Chuan Leekpai became prime minister of a coalition government. In Jan., 1995, parliament approved a package of constitutional reforms that lowered the voting age to 18, guaranteed equal rights for women, and reduced membership in the military-dominated senate. New elections were held in July, 1995, after Chuan's government fell because of a land-reform scandal; the Chart Thai (Thai Nation) party won a slight plurality, and Banharn Silpa-archa became prime minister, heading a seven-party coalition. His government collapsed in Dec., 1996, and he was succeeded by Chavalit Yongchaiyudh. However, Chavalit resigned under pressure in Nov., 1997, and Chuan Leekpai once again became prime minister. A new constitution was approved in Sept., 1997.
Despite its unsteady political climate, Thailand appeared to have one of the strongest economies in SE Asia. However, following years of speculation in the real estate market and growing corruption in government, its currency plummeted in July, 1997, setting off a crisis in Asian financial markets and plunging the country into a deep recession. The International Monetary Fund pledged to provide Thailand with a $17 billion rescue package, and by 2000 the economy was experiencing a recovery, but the economic pain led in a loss of support for the government. Elections in Jan., 2001, resulted in a victory for the Thai Rak Thai party (Thais Love Thais; TRT) and its allies, the Chart Thai and Khwam Wang Mai (New Aspiration) parties. Thaksin Shinawatra of the TRT became prime minister, but an anticorruption commission accused him of concealing his assets, raising the possibility that he would be banned from politics for five years. Thailand's high court, however, cleared him in a close decision in August. The new government has privatized a number of state-owned companies, but it also has been marked by investigations into and disclosures of significant corruption.
In 2004 there were attacks by Muslim separatists in Thailand's three southern provinces. Muslims, who are in the majority in the provinces, complained of discrimination in education and employment. The situation there evolved into an ongoing conflict, exacerbated by the sometimes excessive response of the Thai police and military. Militant attacks against nonsecurity targets as the conflict became prolonged, however, also alienated many Muslims.
In Dec., 2004, areas of S Thailand along the Indian Ocean were devastated by a tsunami; an estimated 8,000 people, some of them foreign tourists, died. The government's response to the disaster and the nation's generally improved economic conditions resulted in strong support for the TRT and the prime minister in the Feb., 2005, parliamentary elections, and the governing coalition increased its majority in the lower house. The continuing attacks by Muslim separatists in the south led the prime minister to assume emergency powers in July, 2005.
Meanwhile, Thai publisher Sondhi Limthongkul, a former ally of the prime minister, began publicly criticizing Thaksin for corruption and poor government performance, first on his television program and, after being forced off the air in Aug., 2005, at public rallies. Thaksin responded with libel suits, and there were attacks on Sondhi's offices. In Dec., 2005, the king, in a rare criticism of the government, rebuked Thaksin for suing Sondhi, and the prime minister subsequently withdrew his lawsuits.
A controversial stock sale (Jan., 2006) by Thaksin's children, who sold a nearly 50% stake in the family communications business to a Singapore-government-owned company and legally avoided taxes on the deal, gave new life to anti-government protests. In February the prime minister called a snap election, but the opposition boycotted the April vote. The TRT won a majority of the seats, but 10% of the constituencies failed to elect a representative (all seats must be filled for a government to be formed) and there was a sizable number of abstentions. Thaksin announced he would step aside and "rest," but he did not resign as prime minister as demanded by the opposition. A second ballot in late April still failed to fill all the seats, leading the king to call on the courts to resolve the problem. In May the Constitutional Court ruled the election invalid.
Thaksin resumed his post later in the month, and a new election was tentatively scheduled for October. Meanwhile the late April election of the senate, intended to be independent but dominated by Thaksin supporters, was marred by vote-buying. In June Thaksin said he would support the proposals by a national commission for the three southern provinces; it recommended establishing a regional administrative body to oversee the provinces, using of Malay as a local "working" government language, and avoiding military responses in favor of resolving the problems that had produced the unrest. In mid-June there was a coordinated string of some 40 bombings in the south.
In mid-September the Thai election commission postponed the October parliamentary elections, but shortly thereafter, with Thaksin abroad, the military overthrew him. Gen. Sonthi Boonyaratglin, the head of the army and close to the king, led the coup. He was named head of the Council of National Security, which under the interim constitution became Thailand's most powerful body. A retired general, Surayud Chulanont, was appointed prime minister in October, and a hand-picked unicameral legislature was also appointed. The same month the new government agreed to talks with Muslim rebels in S Thailand, and then revived a former government agency for the region; the dissolution of the agency had contributed to the current unrest in the south. The policy changes did not, however, reduce rebel attacks, which continued into subsequent years and increased in frequency and brutality.
Meanwhile, in Mar., 2007, Thaksin's wife and others were charged with evading taxes in a 1997 share transfer, and the following month his children were order by a Thai anticorruption committee to pay $616 million in taxes and fines as a result of their 2006 sales of stock in the family telecommunications firm. The government moved in June to seize $1.5 billion in assets belonging to Thaksin and his wife, and also ordered him to return to face corruption charges; he remained in exile. The previous month a court had ordered the TRT party disbanded for breaking the electoral laws in 2006; Thaksin was barred from politics for five years. Warrants were subsequently issued for the arrest of Thaksin and his wife on corruption charges.
In Aug., 2007, Thai voters approved a new constitution in a referendum, which was subsequently endosed by the king. Air Chief Marshal Chalit Pukbhasuk succeeded Sonthi as national security council leader in Oct., 2007. In the parliamentary elections in December, the People Power party (PPP), led by an ally of Thaksin and drawing on Thaksin's rural support, won a plurality of the seats; the vote was seen as a repudiation of the coup. Thaksin's wife returned to Thailand from exile in Jan., 2008. In February the PPP formed a six-party coalition government, with PPP leader Samak Sundaravej as prime minister and many former Thaksin aides in key posts; later that month Thaksin returned to Thailand. In July, one party left the governing coalition because of the PPP's focus on constitutional reform. The opposition, known as Yellow Shirts (yellow being the color traditional associated with the monarchy), began mounting increasing confrontational protests against the government in mid-2008; beginning in August they occupied the grounds of the prime minister's office.
Thai government support for naming the Preah Vihear (Phra Viharn) temple a UNESCO World Heritage site stoked antigovernment demonstrations and led to tensions with Cambodia in July, 2008. Awarded to Cambodia in 1962, the temple is claimed by both nations. The nationalistic outpouring in Thailand, in which opposition groups asserted the government action had undermined Thailand's claim on the temple, led both nations to reinforce their troops along the border near the temple, creating concern about an outbreak of border fighting. In Aug., 2008, both nations agreed to reduce greatly their forces near the temple, but tensions continued. There were subsequent sporadic clashes over the site, most significantly in Feb., 2011, and in Apr., 2011, there were clashes there and at other disputed sites. In Dec., 2011, both governments agreed to withdraw their troops from the disputed areas around Preah Vihear, and a demilitarized zone was established there in July, 2012. Most of the disputed territory was awarded in 2013 to Cambodia by the International Court of Justice. Meanwile, in Aug., 2008, Thaksin and his wife fled Thailand for Great Britain after she was convicted of tax fraud; he had been charged with abuse of power and other crimes and was convicted in absentia of corruption in Oct., 2008.
In Sept., 2008, days of antigovernment protest in Bangkok sparked clashes between anti- and progovernment demonstrators; clashes also occurred in October and November. Prime Minister Samak was dismissed from office in September by the Constitutional Court; it ruled that Samak's hosting of a television cooking show violated Thailand's conflict of interest law. He was succeeded by Somchai Wongsawat, a former judge and Thaksin's brother-in-law. In late November antigovernment protesters also began a blockade of Bangkok's airports, with damaging consequences for Thailand's tourist industry and agricultural exports. Early the following month the Constitutional Court ruled that the PPP and two smaller coalition parties had engaged in vote buying in the last election; Somchai was barred from politics and the three parties dissolved. Yellow Shirt activists subsequently ended their protests and blockades. The opposition Democrat party succeeded in forming a governing coalition later in December; party leader Abhisit Vejjajiva became prime minister.
Thaksin supporters, known as "Red Shirts" for the color they used to distinguish themselves from the Yellow Shirts, subsequently mounted demonstrations against the new government. In late March the protests in Bangkok became significant, and in mid-April protestors forced the cancellation of an Association of Southeast Asian Nations summit; demonstrations were also reported in northern and northeastern provinces. Abhisit declared a state of emergency (which lasted two weeks), and used the military to suppress the protests in the capital. In Nov., 2009, Cambodia's naming of Thaksin as a government adviser strained relations between the two nations again.
In Mar., 2010, Thaksin supporters again mounted signficant demonstations in the capital against Abhisit in an attempt to force him to resign and call new elections; the government again declared a state of emergency. In April the ongoing protests erupted into fighting between the Red Shirts and security forces, and hundreds were injured. Abhisit subsequently placed the army commander in chief in charge of national security. In May, after increasing tensions, the government forcibly reestablished control over Bangkok; in response, protesters set fire to a number of buildings, and there were also riots in a number of cities in NE Thailand (a Red Shirt stronghold). The government subsequently also issued an arrest warrant for Thaksin, on terrorism charges relating to the two-month protest. Not until December was emergency rule lifted in all provinces.
In the June, 2011, elections for the House of Representatives, the pro-Thaksin For Thais party (Phuea Thai party, PTP), led by Thaksin's sister Yingluck Shinawatra, won a majority of the seats and subsequently formed a coalition government with a number of smaller parties; Yingluck became Thailand's first woman prime minister. In the 2011 monsoon season (August–October) unusually heavy rains resulted in weeks of significant flooding in three quarters of the country's provinces; it was the worst flooding in half a century. More than 750 persons died, and some areas continued to be affected into early 2012; the disruption to manufacturing caused an economic slowdown.
In Nov., 2013, the amendment of a political amnesty bill to include Thaksin led to a legislative walkout of opposition Democrats, and sparked demonstrations against the government that continued into 2014 despite the failure of the bill to pass the Senate. In December Yingluck dissolved parliament and announced new elections, which the PTP was expected to win; the Democrats announced a boycott of the elections, and demonstrators attempted to disrupt the preparations for them. In Jan., 2014, the government imposed a state of emergency in Bangkok and surrounding provinces.