an island in the western part of the Malay Archipelago; one of the Greater Sunda Islands. Lying on both sides of the equator, Sumatra is part of Indonesia. Area, 435,000 sq km. Population, 20.8 million (1971). The coastline has slight indentations. There are occasional dunes along the southwestern coast, and coral reefs occur along the shoreline. The numerous small islands near Sumatra have a total area of approximately 30,000 sq km.
The western section of Sumatra consists of a system of mountains—the Barisan and other ranges—stretching along the entire southwestern coast. The mountains are composed chiefly of Paleozoic metamorphic rocks with granitic intrusions. Meso-zoic and Cenozoic extrusive and sedimentary deposits and laterites are common. The island has many volcanoes, some of which are active, including Kerintji (3,800 m). Mud volcanoes and karst plateaus are also found. The eastern part of the island is a level alluvial plain up to 250 km wide, a large part of which—approximately 150,000 sq km—is marshy. The coastal zone and river deltas are submerged at high tide. The climate is equatorial and humid. The mean annual temperature on the plains is 25°–27°C, and the annual precipitation totals 1,500–3,000 mm; in the mountains the annual precipitation may reach 4,000 mm. Sumatra has a dense river network. The principal rivers are the Musi, Hari, Indragiri, and Kampar. Lake Toba is the largest lake.
Two-thirds of Sumatra is forested. The plains up to elevations of 50–60 m have wet tropical forests with multiple strata, sometimes located on marshy ground. There is an abundance of dipterocarps, with some fig, palm, bamboo, and camphor trees. The lower stratum has treelike ferns, and the ground cover consists of ferns and a few grass species. Mangrove forests occur along the coast, and the mountains have forests of evergreen oak and chestnut and communities of laurel, beech, and softwoods. Forests with heavy brush cover and some heather and low ferns are found above 2,500 m. Sections of savanna, in which cogon (Imperata cylindrica) is widely distributed, occur in the comparatively dry intermontane basins. Forest animals predominate in the north, including the Sumatran, or Asian, two-horned rhinoceros, Asiatic elephant, Asiatic tapir, sun bear, water buffalo, pig-tailed macaque, orangutan, and gibbon. Reptiles include large snakes, the flying dragon (Draco volans), and the Malayan, or false, gavial (Tomistoma schlegeli). The bird and insect population is varied. The natural flora and fauna of Sumatra are protected in seven national parks (1969).
The island has large deposits of petroleum (Minas, Kenali-Asam, Talang Akar, and Talang Jimar), natural gas, and coal. The chief crop is rice. Rubber-bearing plants, coconut palms, coffee, and spices are cultivated on plantations. Sumatra supports a fishing industry. The principal cities on the island are Medan, Palembang, and Padang.
L. I. KURAKOVA
Some of the first states in Indonesia, including Srivijaya and Malayu, formed on Sumatra in the second to fifth centuries A.D. Srivijaya subjugated almost all of Sumatra in the seventh century. From the late 13th to early 16th centuries, the Sumatran states were vassals of the empire of Majapahit, which ruled all of Indonesia; independent principalities formed after the empire’s disintegration. Sumatra was a Dutch colony from the early 17th to early 20th centuries. It became part of the Republic of Indonesia when the republic was formed on Aug. 17,1945. During the colonial war against the Republic of Indonesia (1945–59), the Netherlands tried to set up a puppet state on Sumatra in order to keep the island regions under its control. In 1949, Sumatra joined the United States of Indonesia, which became a unitary state—the Republic of Indonesia—in 1950.
The artistic culture of Sumatra has played a significant role in the development of Indonesian art. The typical dwellings of Sumatra are houses on strong poles. They have high, two-sided, saddle-like roofs (among the Toba Bataks), four-sided roofs and ornamental superstructure with four gables (among the Karo Bataks), or several high, saddle-like roofs decorated with ornamental designs (among the Minangkabau). Small brick Buddhist temples from the 11th to 14th centuries have been preserved. Traditional crafts include plaiting, weaving, and jewelry making.