The Malay Archipelago (Indonesian/Malay: Kepulauan Melayu, Kapuluang Malayo) also called Insulindia or the Indo-Australian Archipelago is the archipelago between Mainland Southeast Asia and Australia. It has also been called the "Malay world," "Nusantara", "East Indies" and other names over time. The name was taken from the 19th-century European concept of a Malay race, later based on the distribution of Austronesian languages. Situated between the Indian and Pacific oceans, the archipelago of over 25,000 islands and islets is the largest archipelago by area and fifth by number of islands in the world. It includes Brunei, East Timor, Indonesia, Malaysia, Papua New Guinea, the Philippines, and Singapore The term is largely synonymous with Maritime Southeast Asia. The term "Malay Archipelago" was derived from the archaic European supposition of a "Malay race" (a culturally-similar non-Oceanian subset of the Austronesian peoples), a racial concept proposed by European explorers based on their observations of the influence of the Srivijaya empire, which was based on the island of Sumatra. However, the Malay Archipelago does not include all islands inhabited by the Malay race such as Madagascar and Taiwan, and it includes the islands inhabited by Melanesians such as Maluku Islands and New Guinea. The 19th-century naturalist Alfred Wallace used the term "Malay Archipelago" as the title of his influential book documenting his studies in the region. Wallace also referred to the area as the "Indian Archipelago" and the "Indo-Australian" Archipelago. He included within the region the Solomon Islands and the Malay Peninsula due to physiographic similarities. As Wallace noted, there are arguments for excluding Papua New Guinea for cultural and geographical reasons: Papua New Guinea is culturally quite different from the other countries in the region, and it is geologically not part of the continent of Asia, as the islands of the Sunda Shelf are (see Australia). The archipelago was called the "East Indies" from the late 16th century and throughout the European colonial era.