The kingdom of Thailand was known as Siam until 1939. Some parts of Thailand or Siam was governed by the Khmers, based in what is presently Cambodia, during the 11th and 12th centuries. In 1238, 2 Thai leaders fought against Khmer rulers and founded the 1st self-governing Thai kingdom. Ayutthaya, located north of Bangkok, was the first capital of the kingdom from the early-14th century, until its overthrow by Burmese attackers in 1767. The Burmese were enforced to go out and the monarchy was re-founded. The certain rule lasted in 1932, when it was displaced by a system of constitutional monarchy.

Thailand progressively installed a democratic and pluralistic system of government. Progress was slow, principally owing to the military, which has strongly influenced on Thai politics. The army has taken control of the government 17 times since 1932. During the Cold War democratic governments did not happen very often in the region and Thailand's chief ally, the USA, were more involved in encroaching communism from elsewhere in Southeast Asia. Thailand was an important member of the major regional anti-communist bloc, Association of South-East Asian Nations (ASEAN). Thailand has played an important role in proposing the reformation of ASEAN into a regional trading bloc (see Business).

It was part of a re-alignment of Thai foreign policy contrived by the government of Chatichai Choonhaven, who led from his election in 1988 until his removal in a military coup in February 1991. The coup was a transient event led by army chief General Suchinda Kraprayoon and ended with a return to democratic civilian government in March 1992.

During the next 5 years, Thailand had 4 elections and a variety of coalition governments. King Bhumibol, who is greatly esteemed as a semi-divinity by Thai people, intervened to calm down difficult situations and arguments that seemed to be spiraling out of control. As well as the problems of coalition politics, succeeding governments were also being weakened by growing corruption in Thailand's political and business life. These issues came to a head by the 1997 Asian financial crisis, of which Thailand was 1 of the main victims. The government fell, owing to its inept handling of the crisis.

In 1997 a new constitution limiting the military power was at last put in place. The first elections for a new Senate under this new constitution were held in March of 2000. The poll for the more influential House of Representatives took place in January 2001. The problem of corruption, which has long haunted Thai politics, was reflected in the fact that the winner – the billionaire tycoon, Thaksin Shinawatra – had been officially charged with fraud and tax evasion. Nonetheless, leading the quirkily named Thai Rak Thai (Thais Love Thais) party, Thaksin Shinawatra won a mandate on the promise to support poor farmers and stand up to the IMF.

In spite of his personal troubles, Thaksin has presided over a relatively successful administration and, barring a major political faux pas, is likely to lead Thai Rak Thai in his now second term in office. The Democrats have not been able to overturn Thaksin's huge majority, particularly since their most popular and experienced politician, Chuan Leekpai, retired in 2003.

The economy is booming once again and progress has been made in the foreign policy field, particularly in relations with India, China and Malaysia, with whom co-operative agreements on bilateral mutual security have been signed. Thailand also hosted successful peace talks between the Sri Lanka government and the Tamil Tiger rebels (see Sri Lanka). The border with Myanmar, Thailand's most troublesome neighbour in recent years, closes from time to time due to fighting between the Myanmar army and Shan rebels spilling over into Thai territory. There is also a strongly growing rebellion in the principally Muslim-populated provinces in southern Thailand which border Malaysia. This is quickly becoming a substantial problem for the Thai government.