Thailand, officially the Kingdom of Thailand and historically known as Siam, is a country in Southeast Asia on the Indochinese Peninsula. With a population of almost 70 million, it spans 513,120 square kilometres (198,120 sq mi). Thailand is bordered to the northwest by Myanmar, to the northeast and east by Laos, to the southeast by Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the southwest by the Andaman Sea; it also shares maritime borders with Vietnam to the southeast and Indonesia and India to the southwest. Bangkok is the state capital and largest city.

Southeast Asia is the geographical south-eastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and north-west of mainland Australia which is part of Oceania. Southeast Asia is bordered to the north by East Asia, to the west by South Asia and the Bay of Bengal, to the east by Oceania and the Pacific Ocean, and to the south by Australia and the Indian Ocean. Apart from the British Indian Ocean Territory and two out of 26 atolls of Maldives in South Asia, Maritime Southeast Asia is the only other subregion of Asia that lies partly within the Southern Hemisphere. Mainland Southeast Asia is entirely in the Northern Hemisphere. East Timor and the southern portion of Indonesia are the parts of Southeast Asia that lie south of the Equator.