The 2006 Thai coup d'tat took place on 19 September 2006, when the Royal Thai Army staged a coup d'tat against the elected caretaker government of Prime Minister Thaksin Shinawatra. The coup d'tat, which was Thailand's first non-constitutional change of government in fifteen years since the 1991 Thai coup d'tat, followed a year-long political crisis involving Thaksin, his allies, and political opponents and occurred less than a month before nationwide House elections were scheduled to be held. It has been widely reported in Thailand and elsewhere that General Prem Tinsulanonda, key person in military-monarchy nexus, Chairman of the Privy Council, was the mastermind of the coup. The military cancelled the scheduled 15 October elections, abrogated the 1997 constitution, dissolved parliament and constitutional court, banned protests and all political activities, suppressed and censored the media, declared martial law nationwide, and arrested cabinet members.

The new rulers, led by General Sonthi Boonyaratglin and organised as the Council for Democratic Reform (CDR), issued a declaration on 21 September setting out their reasons for taking power and giving a commitment to restore democratic government within one year. However, the CDR also announced that after elections and the establishment of a democratic government, the council would be transformed into a Council of National Security (CNS) whose future role in Thai politics was not explained. The CNS later drafted an interim charter and appointed retired General Surayud Chulanont as Premier. Martial law was lifted in 41 of Thailand's 76 provinces on 26 January 2007 but remained in place in another 35 provinces.

Elections were held on 23 December 2007, after a military-appointed tribunal outlawed the Thai Rak Thai (TRT) party of Thaksin Shinawatra and banned TRT executives from contesting in elections for five years.

The 2006 coup was named the unfinished coup after another army general Prayut Chan-o-cha staged the 2014 Thai coup d'tat eight years later against the government of Yingluck Shinawatra, Thaksin Shinawatra's sister, removing her government. The 2014 coup had taken over the country for five years, much longer than the 2006 coup, and drafted the junta senates to be involved in the prime minister election.

Thailand ( TY-land, TY-lənd), historically known as Siam (), officially the Kingdom of Thailand, is a country in Southeast Asia spanning 513,120 square kilometres (198,120 sq mi), with a population of almost 70 million. It 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 Myanmar. Thailand also shares maritime borders with Vietnam to the southeast, and Indonesia and India to the southwest. Thailand has experienced multiple coups and military dictatorships. From 2014 to 2019 it was formally under military rule, until the military introduced a new constitution and held elections which established the framework of a parliamentary constitutional monarchy. In practice, however, structural advantages in the constitution have ensured the military's hold on power. Bangkok is the nation's capital and largest city.

Tai peoples migrated from southwestern China to mainland Southeast Asia from the 11th century. Indianised kingdoms such as the Mon, Khmer Empire and Malay states ruled the region, competing with Thai states such as the Kingdoms of Ngoenyang, Sukhothai, Lan Na and Ayutthaya, which also rivalled each other. 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, gradually declining thereafter until being ultimately destroyed in the Burmese–Siamese War. Taksin quickly reunified the fragmented territory and established the short-lived Thonburi Kingdom. He was succeeded in 1782 by Buddha Yodfa Chulaloke, the first monarch of the current Chakri dynasty.

Throughout the era of Western imperialism in Asia, Siam remained the only nation in the region to avoid being colonised by foreign powers, although it was often forced to cede both territory and trade concessions in unequal treaties. The Siamese system of government was centralised and transformed into a modern unitary absolute monarchy in the reign of Chulalongkorn. In World War I, Siam sided with the Allies, a political decision made in order to amend the unequal treaties. Following a bloodless revolution in 1932, it became a constitutional monarchy and changed its official name to Thailand, which was an ally 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 an anti-communist role in the region as a member of the failed SEATO, but since 1975, had sought to improve relations with Communist China and Thailand's neighbors. Apart from a brief period of parliamentary democracy in the mid-1970s, Thailand has periodically alternated between democracy and military rule. Since the 2000s, it has been caught in a series of bitter political conflict between supporters and opponents of Thaksin Shinawatra, which culminated in two coups, in 2014, and the establishment of its current constitution, and ongoing pro-democracy protests.

Thailand is a middle power in global affairs, and a founding member of ASEAN; ranking high in the Human Development Index. It has the second-largest economy in Southeast Asia, and the 22nd-largest in the world by PPP. Thailand is classified as a newly industrialised economy; manufacturing, agriculture, and tourism are leading sectors of the economy.