Or Sumatera; Second-largest island of Indonesia, one of the Sunda Islands; area 473,600 sq km/182,800 sq mi; East of a longitudinal volcanic mountain range is a wide plain; both are heavily forested. Products include rubber, rice, tobacco, tea, timber, tin, and petroleum.
Northern Sumatra is rapidly being industrialized, and the Asakan River (rising in Lake Toba) was dammed for power 1974. The main towns are Palembang, Padang, and Benkuelen.
A Hindu empire was founded in the 8th century, but Islam was introduced by Arab traders from the 13th century and by the 16th century was adopted throughout the island.A mountainous island in western Indonesia.