Sunda Islands, group of islands extending from the Malay Peninsula to the Moluccas southeast of the Asiatic mainland toward New Guinea. They include the Greater Sundas (Sumatra, Java, Borneo, Celebes, and adjacent smaller islands) and the Lesser Sundas (Bali, Lombok, Sumbawa, Sumba, and Flores, Timor, Alor, and adjacent smaller islands). With the exception of Borneo, eastern Sumatra, and nearby areas, they belong to the zone of island arcs and submarine ridges, lying between Asia and Australia, which are geologically unstable and volcanically active. Bounded by the Indian Ocean on the south and west and by the Strait of Malacca, the South China Sea, and the Celebes Sea on the north and east, the islands surround the Java, Flores, and Savu seas. The islands include most of the land area of Indonesia, with only northern and northwestern Borneo not under Indonesian political control. Malaysian cultures and languages predominate in the area.