section_path: Geography/Boundaries
section_name: Boundaries
paragraph_text: Boundaries
  
  Geographically, Southeast Asia is bounded to the southeast by the Australian continent, the boundary between these two regions is most often considered to run through Wallacea.
  
  Geopolitically, the boundary lies between Papua New Guinea and the Indonesian region of Western New Guinea (Papua and West Papua). Both countries share the island of New Guinea.
  
  Islands to the east of the Philippines make up the region of Micronesia. These islands are not biogeographically, geologically or historically linked to mainland Asia, and are considered part of Oceania by the United Nations, The World Factbook, and other organisations. The Oceania region is politically represented through the Pacific Islands Forum, a governing body which, up until 2022, included Australia, New Zealand and all independent territories in Melanesia, Micronesia, and Polynesia. Several countries of Maritime Southeast Asia, such as Indonesia and the Philippines, are dialogue partners of the Pacific Islands Forum, but none have full membership.
  
  Maritime Southeast Asia was often grouped with Australia and Oceania in the mid to late 1800s, rather than with mainland Asia. The term Oceania came into usage at the beginning of the 1800s, and the earlier definitions predated the advent of concepts such as Wallacea.
  
  The non-continental Australian external territories of Christmas Island and Cocos (Keeling) Islands are sometimes considered part of Maritime Southeast Asia, as they lie in much closer proximity to western Indonesia than they do to mainland Australia. They have a multicultural mix of inhabitants with Asian and European Australian ancestry, and were uninhabited when discovered by the British during the 17th century. The islands lie within the bounds of the Australian Plate, and are defined by The World Factbook as the westernmost extent of Oceania. The United Nations also include these islands in their definition of Oceania, under the same subregion as Australia and New Zealand.