Southeast Asia (or Southeastern Asia) is a subregion of Asia, consisting of the countries that are geographically south of China, east of India and north of Australia. The region lies on the intersection of geological plates, with heavy seismic and volcanic activity.

Southeast Asia consists of two geographic regions: Mainland Southeast Asia, also known as Indochina, comprises Cambodia, Laos, Burma (Myanmar), Thailand, Vietnam and Peninsular Malaysia, and Maritime Southeast Asia, which is analogous to the Malay Archipelago, comprises Brunei, East Malaysia, East Timor, Indonesia, the Philippines, and Singapore. Geographically Hong Kong, Macau,and Taiwan are sometimes grouped in the Southeast Asia subregion, although politically they are rarely grouped as such. The same is true for the Andaman and Nicobar Islands of India, and occasionally regions of the Seven Sister States such as Manipur.

Austronesian peoples predominate in this region. The major religions are Buddhism and Islam, followed by Christianity. However, a wide variety of religions are found throughout the region, including many Hindu and animist-influenced practices.