Thailand, officially the Kingdom of Thailand and formerly known as Siam, is a country located at the center of Southeast Asia. It is bordered to the north by Burma 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 Burma. Its maritime boundaries include Vietnam in the Gulf of Thailand to the southeast and Indonesia and India in the Andaman Sea to the southwest.
The country is a kingdom, with most recorded reigns in the world; a constitutional monarchy with King Rama IX, the ninth king of the House of Chakri, who has reigned since 1946, making him the world's longest-serving current head of state and the longest-reigning monarch in Thai history. The king is officially titled Head of State, the Head of the Armed Forces, an Upholder of the Buddhist religion, and the Defender of all Faiths.
The region known as Thailand has been inhabited by humans at least since the Paleolithic period, about 40,000 years ago. Similar to other regions in Southeast Asia, it was heavily influenced by the culture and religions of India, starting with the kingdom of Funan around the 1st century CE.
Kosa Pan presents King Narai's letter to Louis XIV at Versailles, 1 September 1686
Siamese embassy to Louis XIV in 1686, by Nicolas Larmessin.
The ruins of Wat Chaiwatthanaram at Ayutthaya, the city was burned and sacked in 1767 by a Burmese army under the Alaungpaya Dynasty.
Buddhist images at Wat Mahathat built during the Sukhothai period.
After the fall of the Khmer Empire in the 13th century, various states thrived there, such as the various Tai, Mon, Khmer and Malay kingdoms, as seen through the numerous archaeological sites and artifacts that are scattered throughout the Siamese landscape. Prior to the 12th century however, the first Thai or Siamese state is traditionally considered to be the Buddhist kingdom of Sukhothai, which was founded in 1238.
Following the decline and fall of the Khmer empire in the 13th–14th century, the Buddhist Tai kingdoms of Sukhothai, Lanna and Lan Xang were on the ascension. However, a century later, the power of Sukhothai was overshadowed by the new kingdom of Ayutthaya, established in the mid-14th century in the lower Chao Phraya River or Menam area.
Ayutthaya's expansion centered along the Menam while in the northern valley the Lanna Kingdom and other small Tai city-states ruled the area. In 1431, the Khmer abandoned Angkor after the Ayutthaya forces invaded the city. Thailand retained a tradition of trade with its neighbouring states, from China to India, Persia and Arab lands. Ayutthaya became one of the most vibrant trading centres in Asia. European traders arrived in the 16th century, beginning with the Portuguese, followed by the French, Dutch and English.
After the fall of Ayutthaya in 1767 to the Burmese, King Taksin the Great moved the capital of Thailand to Thonburi for approximately 15 years. The current Rattanakosin era of Thai history began in 1782, following the establishment of Bangkok as capital of the Chakri dynasty under King Rama I the Great. According to Encyclopædia Britannica, "A quarter to a third of the population of some areas of Thailand and Burma were slaves in the 17th through the 19th centuries."
Despite European pressure, Thailand is the only Southeast Asian nation that has never been colonized. This has been ascribed to the long succession of able rulers in the past four centuries who exploited the rivalry and tension between French Indochina and the British Empire. As a result, the country remained a buffer state between parts of Southeast Asia that were colonized by the two colonizing powers, Great Britain and France. Western influence nevertheless led to many reforms in the 19th century and major concessions, most notably being the loss of a large territory on the east side of the Mekong to the French and the step-by-step absorption by Britain of the Malay Peninsula.
The losses initially included Penang and eventually culminated in the loss of four predominantly ethnic-Malay southern provinces, which later became Malaysia's four northern states, under the Anglo-Siamese Treaty of 1909.
In 1932, a bloodless revolution carried out by the Khana Ratsadon group of military and civilian officials resulted in a transition of power, when King Prajadhipok was forced to grant the people of Siam their first constitution, thereby ending centuries of absolute monarchy.
During World War II, the Empire of Japan demanded the right to move troops across Thailand to the Malayan frontier. Japan invaded the country and engaged the Thai Army for six to eight hours before Plaek Pibulsonggram ordered an armistice. Shortly thereafter Japan was granted free passage, and on December 21, 1941, Thailand and Japan signed a military alliance with a secret protocol wherein Tokyo agreed to help T