Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainland China, east of the Indian subcontinent, and north-west of mainland Australia. 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 completely in the Northern Hemisphere. East Timor and the southern portion of Indonesia are the only parts that are south of the Equator. The region lies near the intersection of geological plates, with both heavy seismic and volcanic activities. The Sunda Plate is the main plate of the region, featuring almost all Southeast Asian countries except Myanmar, northern Thailand, northern Laos, northern Vietnam, and northern Luzon of the Philippines. The mountain ranges in Myanmar, Thailand, and Peninsular Malaysia are part of the Alpide belt, while the islands of the Philippines are part of the Pacific Ring of Fire. Both seismic belts meet in Indonesia, causing the region to have relatively high occurrences of earthquakes and volcanic eruptions, particularly in the Philippines and Indonesia. It covers about 4,500,000 km2 (1,700,000 sq mi), which is 8% of Eurasia and 3% of Earth's total land area. Its total population is more than 675 million, about 8.5% of the world's population. It is the third most populous geographical region in Asia after South Asia and East Asia. The region is culturally and ethnically diverse, with hundreds of languages spoken by different ethnic groups. Ten countries in the region are members of the Association of Southeast Asian Nations (ASEAN), a regional organisation established for economic, political, military, educational, and cultural integration amongst its members. Southeast Asia is one of the most culturally diverse regions of the world. There are many different languages and ethnicities in the region. Historically, Southeast Asia was significantly influenced by Indian, Chinese, Muslim, and colonial cultures, which became core components of the region's cultural and political institutions. All modern Southeast Asian countries, with the exception of Thailand, were colonized and ruled by European powers. The Spanish ruled the Phillipines for over 300 years until 1898. Much of Southeast Asia was also occupied as part of the Japanese Empire during World War II. In the aftermath, the region was decolonised. Today, Southeast Asia is governed by independent states. Vietnam and Laos are some of the only countries in the world that continue to follow the socialist and communist model.
