The region, together with part of South Asia, was well known by the Europeans as the
East Indies or simply the
Indies until the 20th century. Chinese sources referred the region as 南洋 (
Nanyang), which literally means the Southern Ocean. The mainland section of Southeast Asia is referred as Indochina by European geographer due to its location between China and Indian subcontinent and cultural influences from both neighboring regions. In the 20th century however, the term became more restricted to former
French Indochina territory (Cambodia, Laos, and Vietnam). The maritime section of Southeast Asia is also known as
Malay Archipelago, a term derived from the European concept of a
 Another term for Maritime Southeast Asia is
Insulindia (Indian Islands), used to describe the region between
The term "Southeast Asia" was first used in 1839 by an American pastor Howard Malcolm in his book entitled Travels in South-Eastern Asia. Malcolm only included the Mainland section and excluded the Maritime section in his definition of Southeast Asia.
 The term was officially used in the midst of
World War II by the
Allies, through the formation of
South East Asia Command (SEAC) in 1943.
 SEAC popularised the use of the term "Southeast Asia", although what constituted Southeast Asia in the early days was not fixed, for example the
Philippines and a large part of
Indonesia were excluded by SEAC while
Ceylon was included. However, by the late 1970s, a roughly standard usage of the term "Southeast Asia" and the territories it encompasses had emerged.
 Although from a cultural or linguistic perspective, the definitions of "Southeast Asia" may vary, the most common definitions nowadays include the area represented by the countries (sovereign states and dependent territories) listed below.
Ten of eleven states of Southeast Asia are members of the
Association of Southeast Asian Nations (ASEAN), while
East Timor is an observer state.
Papua New Guinea has stated that it might join ASEAN, and is currently an observer. Sovereignty issues exist over some
territories in the South China Sea.
Taiwan (a disputed region or nation), are also considered as part of the Southeast Asia.
Bandar Seri Begawan
Nay Pyi Daw
* Administrative centre in Putrajaya.
statistical division for Asia based on statistic convenience rather than implying any assumption regarding political or other affiliation of countries or territories:
Southeast Asia is geographically divided into two subregions, namely
Mainland Southeast Asia (or
Maritime Southeast Asia (or the similarly defined
Malay Archipelago) (
Mainland Southeast Asia includes:
Maritime Southeast Asia includes:
Andaman and Nicobar Islands of India are geographically considered part of Maritime Southeast Asia. Eastern
Northeast India have strong cultural ties with Southeast Asia and sometimes considered both
South Asian and Southeast Asian.
Sri Lanka has on some occasions been considered a part of Southeast Asia because of its cultural ties to mainland Southeast Asia.
rest of the island of
New Guinea which is not part of Indonesia, namely, Papua New Guinea, is sometimes included, and so are
Guam, and the
Northern Mariana Islands, which were all part of the
Spanish East Indies with strong cultural and linguistic ties to the region.
The eastern half of Indonesia and East Timor (east of the
Wallace Line) are considered to be biogeographically part of Oceania (
Wallacea) due to its distinctive faunal features.
New Guinea and its surrounding islands are geologically considered as a part of
Australian continent, connected via the
Philippine Sea (Pacific Ocean)
Oceans and Seas in Southeast Asia