Sumatra (Soo'matra, usu. Syoo-may'tra; named from the ancient town of Samudera in the north) is after Borneo the largest island of the East Indian Archipelago or Indonesia, having an area not much less than that of Spain, calculated at 165,600 sq. m. Towards the middle it is crossed lengthwise by the equator; the greatest length is 1115 miles, the greatest breadth 275. An imposing mountain-system, consisting of several nearly parallel ranges (7000 to 10,000 feet high), with intervening plateaus and valleys - forms the framework of the island, which has a bold and frequently precipitous coast towards the west. Seven or eight volcanoes are still active, including Indrapura (the culminating peak of the island, 11,S00 feet), Merapi (the most restless), Pasaman or Mount Ophir (which broke out in 1891), etc. Towards the west the rivers are of necessity short and rapid, but several of the eastward streams grow to imposing rivers in their passage through the plains. They are fed by an abundant rainfall (83 inches at Deli). The flora is exceptionally rich. Vast but too rapidly diminishing areas of the mountain regions are covered with virgin forest, a striking contrast to the wide alluvial prairies. The Dutch expedition of 1877-79 collected 400 varieties of timber. Rice, sugar, coffee, pepper, cocoa-nuts, sago, maize, sweet potatoes, yams, and of late excellent tobacco are cultivated. Gold and coal are worked, the latter especially at Ombilin, united with the west coast by railway in 1891. The petroleum found at Langkat and elsewhere is another source of wealth. Of 112 mammals, 45 are common to Borneo and 39 to Java. The birds and snakes are in the main Bornean. The Bornean forms, however, are almost entirely confined to the eastern side of the island. The Orang-outang and the bru, the true tiger, the Malay bear, the rusa deer, the Malay hog, the tapir, the two-horned Sumatran rhinoceros, and the Sumatran elephant are characteristic forms.
Among the birds are Argus pheasants, hornbills, goat-suckers, and grakles. Both the python (15 to 20 feet long) and the cobra are of frequent occurrence, and the crocodile swarms in many of the rivers. Sumatra is peopled in the main by tribes of the Malay stock, differing very markedly in degree of civilisation, custom, and language. An earlier non-Malay element is represented - the Kubus, a savage forest-dwelling race; the Battas; and the Redjangers. Hindu influences, which have left their mark in ruined temples, religious customs, language, alphabets, etc, began to tell on Sumatra prior to the 7th c. In the 13th Mohammedanism was introduced. The island became known in 1508 through Lopez de Figuera. The Portuguese were ousted by the Dutch towards the close of the 16th c.; though the permanent Dutch occupation was not completely carried out round the coast till 1881, and much of the interior is still semi-independent and unexplored. The Dutch possessions were in the hands of the British between 1811 and 1816, and portions down till 1825. Atjeh, Achin or Atcheen (q.v.), only subdued after a long war (1875-79) and not yet pacified in 1894, was formed into a government in 1881. The total pop. of Sumatra and the adjacent islands is estimated at 3,200,000 (Achin, 110,800; West Coast, 1,527,500; East Coast, 421,000; Bencoolen, 162,400, &c). Chief centres of population are Padang (150,000), Achin (10,000), Bencoolen (12,000), and Palem-bang (43,000). See Marsden's History (1783), the memoir of Sir Stamford Raffles; Wallace's Malay Archipelago and Australasia; and Forbes, A Naturalist's Wanderings (1885).