provinsi (“province”), east-central Sumatra, Indonesia. It is bounded by the provinces of Jambi on the south, Sumatera Barat (West Sumatra) on the west, Sumatera Utara (North Sumatra) on the north and northwest, the Malacca Strait on the east, and the Berhala Strait on the southeast. Riau provinsi includes the Riau Islands, an archipelago lying at the southern entrance to the Strait of Malacca. The Riau Islands are separated from Singapore (to the north) by the Singapore Strait and from Sumatra (south and west) by the Berhala Strait. The principal islands of the Riau group are Bintan, Batam, and Karimun. Riau provinsi also includes the Lingga, Singkep, Rupat, and Bengkalis islands in the Strait of Malacca, and the Tambelan, Anambas, and Natuna islands in the South China Sea.The region formed part of the Buddhist Śrīvijaya empire, with its capital at Palembang (Sumatra), and served as a base for the conquest of Hindu kingdoms on the Malay Peninsula in the 7th century. The Hindu Majapahit empire of eastern Java established supremacy over the region with the fall of the Śrīvijaya empire in the 14th century. Muslim states were established in the 16th century after the disintegration of the Majapahit empire. When the Portuguese seized the Malay state of Malacca in 1511, its last sultan retained Johore on the Malay Peninsula and the Riau Islands at its southern tip. The Dutch arrived in 1596, and the British followed shortly afterward. Interpower rivalry and attacks by sea pirates adversely affected the fortunes of the region, which came under Dutch control by the end of the 18th century. After an interval of Japanese occupation during World War II, the province was incorporated into the newly formed Republic of Indonesia in 1950.The Batak Plateau and the Padang Highlands of the Barisan Mountains situated along its western boundary constitute the only major uplands in the province. The Tiga Puluh Mountains, with an average elevation of 2,369 feet (722 m), thrust northward near the province's south-central boundary. A belt of swamps, fed by the Rokan, Tapung, Siak, Kampar, and Indragiri rivers flowing eastward from the highlands, extends inward from the coast to a maximum width of about 150 miles (240 km); swamps also cover the greater part of Rupat and Bengkalis islands. The region is subject to occasional flooding, and the coast is deeply indented by estuaries. The swamp vegetation comprises sedge, pandanus, rattan, and ferns; dense bamboo thickets border the swamps at many places, and the estuaries are dotted with mangroves. Agriculture is the principal occupation; rice, corn (maize), cassava, soybeans, copra, gambier (dye), and pepper are produced. There is also some logging and fishing. The major large-scale industries are the mining of tin and bauxite, respectively, on Singkep and Bintan islands, and petroleum extraction from fields near Pakanbaru, the provincial capital. Sungai Pakning and Dumai have oil refineries. Other industries include food processing, paper making, and wood carving. Internal transport is mainly by riverboat; roads are confined mainly to the hinterland around Pakanbaru. A number of indigenous ethnic groups make up the population, which is predominantly Muslim. There are also many Coastal Malay and Chinese. Area 36,510 square miles (94,561 square km). Pop. (1995 est.) 3,924,600.
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