Southeast Asia or Southeastern Asia is a sub region 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 the following countries: Brunei ÔÇô is a tiny oil-rich sultanate in Borneo. Cambodia ÔÇô a country recovering from decades of war and home of Angkor.