Thailand, officially the Kingdom of Thailand and formerly known as Siam (until 1939 and again from 1946 to 1948), is a country at the center of the Indochinese peninsula in Southeast Asia. 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 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. The capital and largest city is Bangkok. With around 69 million people, Thailand is the 20th-most-populous country in the world. Thai people migrated from southwestern China to mainland Southeast Asia over a period of many centuries. The oldest known mention of their presence in the region by the exonym Siamese is in a 12th-century inscription at the Khmer temple complex of Angkor Wat in Cambodia, which refers to syam, or dark brown, people. Various Indianised kingdoms such as the Mon, the Khmer Empire and Malay states ruled the region, competing with Thai states such as Ngoenyang, the Sukhothai Kingdom, the Kingdom of Chiang Mai, Lan Na and the Ayutthaya Kingdom, which also fought each other. Europeans arrived in the 16th century, beginning with a Portuguese diplomatic mission to Ayutthaya in 1511. The ensuing centuries saw various European colonial powers vying for control of the region, with Thailand sustaining territorial losses to the French and British, but remaining the only Southeast Asian state to avoid colonization. Starting with the reign of King Rama IV in the mid-19th century, Thailand embarked on a nation-building campaign to modernize along Western lines. This culminated with the end of absolute monarchy in 1932 and the establishment of a constitutional monarchy. However, the following sixty years saw almost continuous military rule punctuated by periods of parliamentary democracy, with the most recent coup occurring in May 2014.