The Indian Ocean,
together with the Mediterranean, has connected people since ancient times, whereas the Atlantic and Pacific have had the roles of barriers or
mare incognitum. The written history of the Indian Ocean has been
Eurocentric and largely dependent on the availability of written sources from the
European colonial era. This history is often divided into an ancient period followed by an Islamic period; the subsequent colonial-era periods are often subdivided into
Portuguese,
Dutch, and
British periods. Milo Kearney argues that the
postwar time period can also be split into a period of competition for oil during the
Cold War followed by American dominance. A concept of an "Indian Ocean World" (IOW), similar to that of the "
Atlantic World", exists but emerged much more recently and is not well established. The IOW is, nevertheless, sometimes referred to as the "first global economy" and was based on the monsoon which linked Asia, China, India, and
Mesopotamia. It developed independently from the European global trade in the Mediterranean and Atlantic and remained largely independent from them until European 19th-century colonial dominance. The diverse history of the Indian Ocean is a unique mix of cultures, ethnic groups, natural resources, and shipping routes. It grew in importance beginning in the 1960s and 1970s and, after the Cold War, it has undergone periods of political instability, most recently with the emergence of India and China as regional powers.
First settlements Pleistocene fossils of
Homo erectus and other pre–
H. sapiens hominid fossils, similar to
H. heidelbergensis in Europe, have been found in India. According to the
Toba catastrophe theory, a supereruption c. 74,000 years ago at
Lake Toba, Sumatra, covered India with volcanic ashes and wiped out one or more lineages of such archaic humans in India and Southeast Asia. The
Out of Africa theory states that
Homo sapiens spread from Africa into mainland Eurasia. The more recent
Southern Dispersal or
Coastal hypothesis instead advocates that modern humans spread along the coasts of the Arabic Peninsula and southern Asia. This hypothesis is supported by
mtDNA research which reveals a rapid dispersal event during the
Late Pleistocene (11,000 years ago). This coastal dispersal began in East Africa 75,000 years ago and occurred intermittently from estuary to estuary along the northern perimeter of the Indian Ocean at a rate of per year. It eventually resulted in modern humans migrating from
Sunda over
Wallacea to
Sahul (Southeast Asia to Australia). Since then, waves of migration have resettled people and, clearly, the Indian Ocean littoral had been inhabited long before the first civilisations emerged. 5000–6000 years ago six distinct cultural centres had evolved around the Indian Ocean: East Africa, the Middle East, the Indian Subcontinent, South East Asia, the Malay World and Australia; each interlinked to its neighbours. Food globalisation began on the Indian Ocean littoral c. 4,000 years ago. Five African crops —
sorghum,
pearl millet,
finger millet,
cowpea and
hyacinth bean — somehow found their way to
Gujarat in India during the
Late Harappan (2000–1700 BCE). Gujarati merchants evolved into the first explorers of the Indian Ocean as they traded African goods such as ivory, tortoise shells, and slaves.
Broomcorn millet found its way from Central Asia to Africa, together with chicken and
zebu cattle, although the exact timing is disputed. Around 2000 BCE
black pepper and
sesame, both native to Asia, appear in Egypt, albeit in small quantities. Around the same time the
black rat and the
house mouse emigrate from Asia to Egypt. Banana reached Africa around 3000 years ago.
Negritos are thought to be the first inhabitants of the
Andaman Islands, having emigrated from the mainland tens of thousands of years ago. At least eleven prehistoric tsunamis have struck the Indian Ocean coast of Indonesia between 7400 and 2900 years ago. Analysing sand beds in caves in the Aceh region, scientists concluded that the intervals between these tsunamis have varied from series of minor tsunamis over a century to dormant periods of more than 2000 years preceding megathrusts in the Sunda Trench. Although the risk for future tsunamis is high, a major megathrust such as the one in 2004 is likely to be followed by a long dormant period. A group of scientists have argued that two large-scale impact events have occurred in the Indian Ocean: the
Burckle Crater in the southern Indian Ocean in 2800 BCE and the Kanmare and Tabban craters in the
Gulf of Carpentaria in northern Australia in 536 CE. Evidences for these impacts, the team argue, are micro-ejecta and
Chevron dunes in southern Madagascar and in the Australian gulf. Geological evidences suggest the tsunamis caused by these impacts reached above sea level and inland. The impact events must have disrupted human settlements and perhaps even contributed to
major climate changes.
Antiquity The history of the Indian Ocean is marked by maritime trade; cultural and commercial exchange probably date back at least seven thousand years. Human culture spread early on the shores of the Indian Ocean and was always linked to the cultures of the Mediterranean and the Persian Gulf. Before , cultures on its shores were only loosely tied to each other. Bronze, for example, was developed in Mesopotamia but remained uncommon in Egypt before 1800 BCE. During this period, independent, short-distance oversea communications along its
littoral margins evolved into an all-embracing network. The début of this network was not the achievement of a centralised or advanced civilisation but of local and regional exchange in the Persian Gulf, the Red Sea, and the Arabian Sea. Sherds of
Ubaid (2500–500 BCE) pottery have been found in the western Gulf at
Dilmun, present-day
Bahrain; traces of exchange between this trading centre and
Mesopotamia. The
Sumerians traded grain, pottery, and
bitumen (used for
reed boats) for copper, stone, timber, tin, dates, onions, and pearls. Coast-bound vessels transported goods between the
Indus Valley civilisation (2600–1900
BCE) in the Indian subcontinent (modern-day Pakistan and Northwest India) and the Persian Gulf and Egypt. The
Rub' al Khali desert isolates the southern parts of the Arabic Peninsula and the Indian Ocean from the Arabic world. This encouraged the development of maritime trade in the region linking the Red Sea and the Persian Gulf to East Africa and India. The
monsoon, from
mawsim, the Arabic word for season, was used by sailors long before being "discovered" by Hippalus in the 1st century. Indian wood have been found in Sumerian cities, there is evidence of Akkad coastal trade in the region, and contacts between India and the Red Sea dates back to 2300 B.C. The archipelagoes of the central Indian Ocean, the Laccadive and Maldive islands, were probably populated during the 2nd century B.C. from the Indian mainland. They appear in written history in the account of merchant
Sulaiman al-Tajir in the 9th century but the treacherous reefs of the islands were most likely cursed by the sailors of Aden long before the islands were even settled. with ancient India according to the
Periplus of the Erythraean Sea 1st century CE
Periplus of the Erythraean Sea, an
Alexandrian guide to the world beyond the Red Sea — including Africa and India — from the first century CE, not only gives insights into trade in the region but also shows that Roman and Greek sailors had already gained knowledge about the
monsoon winds. In the 2nd or 1st century BCE,
Eudoxus of Cyzicus was the first Greek to cross the Indian Ocean. The probably fictitious sailor
Hippalus is said to have learnt the direct route from
Arabia to India around this time. During the 1st and 2nd centuries AD intensive
trade relations developed between
Roman Egypt and the
Tamil kingdoms of the
Cheras,
Cholas and
Pandyas in
Southern India. Like the Indonesian people above, the western sailors used the monsoon to cross the ocean. The unknown author of the
Periplus of the Erythraean Sea describes this route, as well as the commodities that were traded along various commercial ports on the coasts of the Horn of Africa and India circa 1 CE. Among these trading settlements were
Mosylon and
Opone on the Red Sea littoral.
Maldivians, on their annual trade trip, took their oceangoing trade ships to
Sri Lanka rather than mainland India, which is much closer, because their ships were dependent of the
Indian Monsoon Current. Arabic missionaries and merchants began to
spread Islam along the western shores of the Indian Ocean from the 8th century, if not earlier. A
Swahili stone mosque dating to the 8th–15th centuries has been found in
Shanga, Kenya. Trade across the Indian Ocean gradually introduced Arabic script and rice as a
staple in Eastern Africa. Muslim merchants traded an estimated 1,000 African slaves annually between 800 and 1700, a number that grew to approximately 4,000 during the 18th century, and 3,700 during the period 1800–1870. Slave trade also occurred in the eastern Indian Ocean before the Dutch settled there around 1600, but the volume of this trade is unknown. From 1405 to 1433 admiral
Zheng He said to have led large fleets of the
Ming dynasty on several
treasure voyages through the Indian Ocean, ultimately reaching the coastal countries of East Africa. . The Portuguese navigator
Vasco da Gama rounded the
Cape of Good Hope during his first voyage in 1497 and became the first European to sail to India. The
Swahili people he encountered along the African east coast lived in a series of cities and had established trade routes to India and to China. Among them, the Portuguese kidnapped most of their pilots in coastal raids and on board ships. A few of the pilots were gifts by local Swahili rulers, including the sailor from Gujarat, a gift by a
Malindi ruler in Kenya, who helped the Portuguese to reach India. In expeditions after 1500, the Portuguese attacked and colonised cities along the African coast. European slave trade in the Indian Ocean began when Portugal established
Estado da Índia in the early 16th century. From then until the 1830s, slaves were exported from Mozambique annually and similar figures has been estimated for slaves brought from Asia to the Philippines during the
Iberian Union (1580–1640). on 29 November 1810 during the
Napoleonic Wars The establishment of the
Dutch East India Company in the early 17th century led to a quick increase in the volume of the slave trade in the region. There were perhaps up to slaves in various
Dutch colonies during the 17th and 18th centuries in the Indian Ocean. For example, some 4,000 African slaves were used to build the
Colombo fortress in
Dutch Ceylon. Bali and neighbouring islands supplied regional networks with slaves 1620–1830. Indian and Chinese slave traders supplied Dutch Indonesia with perhaps slaves during the 17th and 18th centuries.
Late modern era 's population has increased from 20,000 people in 1987 to more than 220,000 people in 2020. Scientifically, the Indian Ocean remained poorly explored before the
International Indian Ocean Expedition in the early 1960s. However, the
Challenger expedition 1872–1876 only reported from south of the polar front. The
Valdivia expedition 1898–1899 made deep samples in the Indian Ocean. In the 1930s, the John Murray Expedition mainly studied shallow-water habitats. The
Swedish Deep Sea Expedition 1947–1948 also sampled the Indian Ocean on its global tour and the Danish
Galathea sampled deep-water fauna from Sri Lanka to South Africa on its second expedition 1950–1952. The Soviet research vessel
Vityaz also did research in the Indian Ocean. The construction of the canal introduced many non-indigenous species into the Mediterranean. For example, the goldband goatfish (
Upeneus moluccensis) has replaced the red mullet (
Mullus barbatus); since the 1980s huge swarms of
scyphozoan jellyfish (
Rhopilema nomadica) have affected tourism and fisheries along the Levantian coast and clogged power and desalination plants. Plans announced in 2014 to
build a new, much larger Suez Canal parallel to the 19th-century canal will most likely boost the economy in the region but also cause ecological damage in a much wider area. on
Diego Garcia in 1971, before the British
expelled the islanders. He spoke a
French-based creole language and his ancestors were likely brought as slaves in the 19th century. Throughout the colonial era, islands such as
Mauritius were important shipping nodes for the Dutch, French, and British. Mauritius, an inhabited island, became populated by slaves from Africa and
indenture labour from India. The end of
World War II marked the end of the colonial era. The British left Mauritius after granting independence to the island on 12 March 1968 and with 70% of the population of Indian descent, Mauritius became a close ally of India. In the 1980s, during the Cold War, the South African regime acted to destabilise several island nations in the Indian Ocean, including the Seychelles, Comoros, and Madagascar. India intervened in Mauritius to prevent a coup d'état, backed up by the United States who feared the Soviet Union could gain access to
Port Louis and threaten the U.S. base on
Diego Garcia.
Iranrud was an unrealised plan by Iran and the Soviet Union to build a canal between the Caspian Sea and the Persian Gulf. Testimonies from the colonial era are stories of African slaves, Indian indentured labourers and white settlers. But, while there was a clear racial line between free men and slaves in the Atlantic World, this delineation is less distinct in the Indian Ocean — there were Indian slaves and settlers as well as black indentured labourers. There were also a string of prison camps across the Indian Ocean, such as
Cellular Jail in the Andamans, in which prisoners, exiles, POWs, forced labourers, merchants and people of different faiths were forcefully united. On the islands of the Indian Ocean, therefore, a trend of
creolisation emerged. On 26 December 2004, fourteen countries around the Indian Ocean were hit by a wave of
tsunamis caused by the
2004 Indian Ocean earthquake. The waves radiated across the ocean at speeds exceeding , reached up to in height, and resulted in an estimated 236,000 deaths. In the late 2000s, the ocean evolved into a hub of
pirate activity. By 2013, attacks off the Horn region's coast had steadily declined due to active private security and international navy patrols, especially by the
Indian Navy.
Malaysia Airlines Flight 370, a
Boeing 777-2H6ER with 239 occupants on board, disappeared on 8 March 2014 and is alleged to have crashed into the southern Indian Ocean about from the coast of southwest
Western Australia. Despite an extensive search, the whereabouts of the remains of the aircraft is unknown. The
Sentinelese people of
North Sentinel Island, which lies near
South Andaman Island in the Bay of Bengal, have been called by experts the most
isolated people in the world. The sovereignty of the
Chagos Archipelago in the Indian Ocean is
disputed between the United Kingdom and
Mauritius. In February 2019, the
International Court of Justice in
The Hague issued an advisory opinion
stating that the UK must transfer the Chagos Archipelago to Mauritius. ==Geopolitics==