Sumatra (Sumatera in Bahasa Indonesia) is the world's six largest island, with an area of 473,481 square km and a population of around 50 million. The Bukit Barisan mountains, stretching parallel to the island's western coast, contain several active volcanoes. Sumatra is located on the "Pacific Rim of Fire", a seismic active zone. The Lake Toba eruption (between 75,500 and 67,500 BP) is regarded one of the most destructive volcanic eruptions in history. The tsunami of 2004 had its epicenter in the Indian Ocean just west of Sumatra and caused severe damage, especially in and near Aceh.
Sumatra once was connected to the Asian mainland; and because of changes in the sea level, then at times was an island, at times connected to Java, the Malay Peninsula and even Borneo. As late as 17,000 BC, such a connection still was the case [Cribb].
The island consists of diverse ecozones : the eastern coastal lands, the central highlands, the western coast. Throughout most of its history, Sumatra was divided into a number of polities; only under Dutch colonial rule, after the conquest of Aceh in 1903/1908 was the island politically united.
Humans arrived on Sumatra "long before it became an island" [Crossroads p.32]. Paleolithic and Mesolithic stone tools have been found at a number of places. The Neolithic (farming) is believed to have arrived with Austronesian settlers [2000-500 BCE, Crossroads p.32]; the usage of metal tools began some time after 500 BCE.
A Sanskrit text of the Ramayana from the third century BCE refers to a gold-rich island or region called Suvarnadvipa. In later sources, this term was used specifically for Sumatra [Crossroads]. During the first millennium, Sumatra did export gold and forest products. The oldest known polity on Sumatra was Kantoli (S. Sumatra), c.500 CE. Vaishnavite Hinduism and Mahayana Buddhism early on competed for influence.
From the 7th century to 1290, the maritime Empire of Srivijaya (Palembang is believed to have been the capital) controlled much of Srivijaya (except parts of the west coast). Srivijaya was a center of Buddhist studies. A number of stone inscriptions in Kawi script scattered over Sumatra refer to Srivijaya. In the 1025, Srivijaya was raided and briefly controled by the South Indian Chola Dynasty. The capital of Srivijaya seems to have moved from Palembang to Jambi.
Marco Polo in 1292 visited Samudra Pasai (northern Sumatra, which he called Java minor); his account reports nearby Ferlec (= Perlac) already having been Muslim. When Ibn Battuta visited Samudra Pasai in 1345, it was already a Muslim polity ruled by a Sultan and it had been since at least 1326, as attested by a local gravestone [Crossroads]. Visitors from the 13th to the 16th century also attest a great difference in lifestyle, as well as animosity, between peoples living on the coast and those dwelling in the interior. People dwelling in the interior, most notably the Minangkabau and the Batak, maintained their national identities into the 20th century.
From 1400 to 1511, The Sultanate of Malacca (Melaka) ruled much of Sumatra's east coast. The Sultanate of Palembang was independent. In 1511 the Portuguese conquered Malacca; the Sultan moved his capital to Johor River. The new Sultanate of Johor controlled much of the central section of Java's east coast. In northern Sumatra, Samudra Pasai fell to the Portuguese in 1521. The Sultanate of Aceh emerged as a regional power. In 1641, the V.O.C., allied with Johor, expelled the Portuguese from Malacca and took over the city. The British established a trading factory in Bencoolen (Western Sumatra) 1685. In 1725, the Sultanate of Siak seceded from Johor. In 1799 the V.O.C. declared bankrupcy, and her possessions were taken over by the Batavian Republic (Dutch East Indies). In 1814, the Sultanate of Aru (Deli) seceded from Siak. In 1819 the Sultanate of Riau-Linggor seceded from Johor. In an 1824 deal, the British ceded Bencoolen to the Dutch, in return for the Dutch ceding Malacca to the British.
In 1825 the Dutch East Indies conquered and annexed Palembang; from 1833 the Dutch treated Jambi as a sultanate separate from Riau-Linggor; in 1858 Siak accepted a Dutch protectorate; in 1871 the British accepted the Dutch claim on Aceh. The conquest of Aceh, begun in 1873, lasted until 1903/1908. The Sultanate of Jambi was annexed in 1906. The inhabitants of islands west of Sumatra, such as Nias, are regarded as being a modern Megalithic society.
The Dutch developed Deli as a major plantation center (among others : tobacco) and tapped the island's oil reserves (Royal Dutch-Shell). The Dutch administration brought workers in significant numbers to Sumatra, from other parts of the archipelago.
Indonesia became independent in 1949. A Sumatran, Mohammad Hatta, had played a leading role in Indonesia's independence movement. Indonesia's capital is Jakarta; the country's economy is concentrated on heavily populated Java. From the 1950s to 1980s, the Transmigrasi program resettled millions of Javanese families on the larger, but lesser populated island of Sumatra. The island population rose from about 20 million in 1971 to about 50 million in 2010, with extraordinary growth rates in the 1970s and 1980s, due to Transmigrasi.