The Malay Archipelago is a name given to the archipelago located between mainland Southeastern Asia (Indochina) and Australia. Straddling the Indian and Pacific Oceans, this group of some 20,000 islands, the world's largest archipelago by area, constitutes the territories of Indonesia, the Philippines, Singapore, Brunei, Malaysia, East Timor, and most of Papua New Guinea. There are, however, arguments for excluding the last-named country for cultural and geographical reasons: Papua New Guinea is culturally quite different from the other countries in the region, and the island of New Guinea itself is geologically not part of the continent of Asia, as the islands of the Sunda Shelf are (see Australia (continent)).
The archipelago is sometimes also known as the East Indies, but some authorities apply a much broader meaning to this term by including Indochina, the Indian subcontinent, and even areas as far west as Iranian Baluchistan.
The archipelago encompasses many groups which may be considered archipelagoes in their own right. The major ones are:
The archipelago's area is more than 2 million km², and its total population is more than 300,000,000+. The biggest islands in the archipelago are New Guinea (if included), Borneo, and Sumatra. The most heavily populated island is Java.
Geologically the archipelago is one of the most active volcanic regions in the world. Geological uplifts in the region have also produced some impressive mountains, culminating in Mount Kinabalu in Sabah with a height of 4 101 m (or Puncak Jaya in Papua at 4 884 m, if New Guinea is included).
The climate throughout the archipelago, owing to its position astride the equator, is tropical. It is notably rainier in the west than in the east, however.
The region known as Maritime Southeast Asia is more or less coextensive with the Malay Archipelago.
Often, the mainland part of Malaysia, which is known as Malaya, is included as part of Maritime Southeast Asia in order that all the non-Oceanian Austronesian peoples can be included together in one cultural region.