Thailand,[a] officially the Kingdom of Thailand and formerly known as Siam,[b] is a country in Southeast Asia. Located at the centre of the Indochinese Peninsula, it is composed of 76 provinces, and covers an area of 513,120 square kilometres (198,120 sq mi), and a population of over 66 million people. Thailand is the world’s 50th-largest country by land area, and the 22nd-most-populous country in the world. The capital and largest city is Bangkok, a special administrative area. Thailand is bordered to the north by Myanmar and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the west by the Andaman Sea and the southern extremity of Myanmar. Its maritime boundaries include Vietnam in the Gulf of Thailand to the southeast, and Indonesia and India on the Andaman Sea to the southwest. Nominally, Thailand is a constitutional monarchy and parliamentary democracy; however, in recent history, its government has experienced multiple coups and periods of military dictatorships.
Tai peoples migrated from southwestern China to mainland Southeast Asia from the 11th century; the oldest known mention of their presence in the region by the exonym Siamese dates to the 12th century. Various Indianised kingdoms such as the Mon kingdoms, Khmer Empire and Malay states ruled the region, competing with Thai states such as the Kingdoms of Ngoenyang, Sukhothai, Lan Na and Ayutthaya, which rivalled each other. Documented European contact began in 1511 with a Portuguese diplomatic mission to Ayutthaya, which became a regional power by the end of the 15th century. Ayutthaya reached its peak during cosmopolitan Narai’s reign (1656–1688), gradually declining thereafter until being ultimately destroyed in the 1767 Burmese–Siamese War. Taksin (r. 1767–1782) quickly reunified the fragmented territory and established the short-lived Thonburi Kingdom. He was succeeded in 1782 by Buddha Yodfa Chulaloke (r. 1782–1809), the first monarch of the current Chakri dynasty.
Through the 18th and 19th centuries, Siam faced imperialist pressure from France and the United Kingdom, including many unequal treaties with Western powers and forced concessions of territory; it nevertheless remained the only Southeast Asian country to avoid direct Western rule. Siamese system of government was centralized and transformed into modern unitary absolute monarchy in the reign of Chulalongkorn (r. 1868–1910). Siam joined World War I siding with the allies, a political decision to amend the unequal treaties. Following a bloodless revolution in 1932, Siam became a constitutional monarchy and changed its official name to “Thailand”. Thailand was a satellite of Japan in World War II. In the late 1950s, a military coup under Field Marshal Sarit Thanarat revived the monarchy’s historically influential role in politics. Thailand became a major ally of the United States, and played a key anti-communist role in the region as a member of the Southeast Asia Treaty Organization (SEATO). Apart from a brief period of parliamentary democracy in the mid-1970s, Thailand has periodically alternated between democracy and military rule. Since the 2000s, Thailand has been caught in a bitter political conflict between supporters and opponents of Thaksin Shinawatra, which culminated in two coups, most recently in 2014 and the establishment of its current and 20th constitution and faces the ongoing 2020 Thai protests.
Thailand is a founding member of the Association of Southeast Asian Nations (ASEAN) and remains a major ally of the United States. Despite comparatively sporadic changes in leadership, it is considered a regional power in Southeast Asia and a middle power in global affairs. With a high level of human development, the second-largest economy in Southeast Asia, and the 20th-largest in the world by PPP, Thailand is classified as a newly industrialized economy; manufacturing, agriculture, and tourism are leading sectors of the economy.
There is evidence of continuous human habitation in present-day Thailand from 20,000 years ago to the present day.:4 The earliest evidence of rice growing is dated at 2,000 BCE. Bronze appeared circa 1,250–1,000 BCE. The site of Ban Chiang in northeast Thailand currently ranks as the earliest known centre of copper and bronze production in Southeast Asia. Iron appeared around 500 BCE. The Kingdom of Funan was the first and most powerful Southeast Asian kingdom at the time (2nd century BCE). The Mon people established the principalities of Dvaravati and Kingdom of Hariphunchai in the 6th century. The Khmer people established the Khmer empire, centred in Angkor, in the 9th century. Tambralinga, a Malay state controlling trade through the Malacca Strait, rose in the 10th century. The Indochina peninsula was heavily influenced by the culture and religions of India from the time of the Kingdom of Funan to that of the Khmer Empire.
The Thai people are of the Tai ethnic group, characterised by common linguistic roots. Chinese chronicles first mention the Tai peoples in the 6th century BCE. While there are many assumptions regarding the origin of Tai peoples, David K. Wyatt, a historian of Thailand, argued that their ancestors which at the present inhabit Laos, Thailand, Myanmar, India, and China came from the Điện Biên Phủ area between the 5th and the 8th century. Thai people began migrating into present-day Thailand around the 11th century, which Mon and Khmer people occupied at the time. Thus Thai culture was influenced by Indian, Mon, and Khmer cultures.
According to French historian George Cœdès, “The Thai first enter history of Farther India in the eleventh century with the mention of Syam slaves or prisoners of war in Champa epigraphy, and “in the twelfth century, the bas-reliefs of Angkor Wat” where “a group of warriors” are described as Syam.