The Indian Ocean World, one of the twelve divisions of the Earth, is centered on the Indian Ocean and encompasses Madagascar, several small island groups, Maritime East Africa, Southeastern Arabia, Southern India, Sri Lanka, and Aceh—the northernmost tip of Sumatra. Its southernmost point is Kerguelen Island.

To the north of Madagascar, the island nations of the Comoros and the Seychelles are situated in the western Indian Ocean, while Mauritius lies to the east of the great island.

On the African mainland, the region includes portions of Mozambique, Malawi, Tanzania, Kenya, and Somalia, all of which also have cultural and historical ties to Afroasia.

The Arabian nations of Yemen and Oman face the heart of the Indian Ocean World, with their division aligning with the traditional boundary separating North India from South India and Sri Lanka.

To the west of Southern India, the Maldives form a prominent island chain within this maritime world.

Along the northeastern boundary, only Aceh, the northwesternmost tip of Sumatra, belongs to the Indian Ocean World, distinguishing it from the rest of the Indonesian archipelago.

HistoryAtlas contains 1,059 entries for the Indian Ocean World from the Paleolithic period to 1899.

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Primitive humans first migrate to the Indian subcontinent between 400,000 and 200,000 BCE; some of them possibly sail to southern India from eastern Africa.

The Moderns are taller, more slender, and less muscular than the Neanderthals, with whom they share—perhaps uneasily—the Earth.

Though their brains are smaller in overall size, they are heavier in the forebrain, a difference that may allow for more abstract thought and the development of complex speech.

Yet, the inner world of the Neanderthals remains a mystery—no one knows the depths of their thoughts or how they truly expressed them.

Modern humans begin to move out of the Horn of Africa, some traveling south, others moving east into Arabia along the Indian Ocean’s 'Coastal Express' route, eventually to arrive in Australia; others penetrate northeast into West Asia, a route presumably rendered impassable in former times by tough, strong, spear-wielding Neanderthals.

The descendants of the immigrants to West Asia who had remained in the south (or taken the southern route) had spread generation by generation around the coast of Arabia and the Iranian plateau until they reached India.

One of the groups that had gone north (east Asians were the second group) had ventured inland and radiated to Europe, eventually displacing the Neanderthals.

They had also radiated to India from Central Asia.

The former group headed along the southeast coast of Asia, reaching Australia between fifty-five thousand and thirty thousand years ago, with most estimates placing it about forty-six thousand to forty-one thousand years ago.

Sea level is much lower during this time, and most of Maritime Southeast Asia is one land mass known as the lost continent of Sunda.

The settlers probably continued on the coastal route southeast until they reached the series of straits between Sunda and Sahul, the continental land mass that was made up of present-day Australia and New Guinea.

The widest gaps are on the Weber Line and are at least ninety kilometers wide, indicating that settlers had knowledge of seafaring skills.

Archaic humans such as Homo erectus never reached Australia.

If these dates are correct, Australia was populated up to ten thousand years before Europe.

This is possible because humans avoided the colder regions of the North favoring the warmer tropical regions to which they were adapted given their African homeland.

Another piece of evidence favoring human occupation in Australia is that about forty-six thousand years ago, all large mammals weighing more than one hundred kilograms suddenly became extinct.

The new settlers were likely to be responsible for this extinction.

Many of the animals may have been accustomed to living without predators and become docile and vulnerable to attack (as will occur later in the Americas).

The small population of moderns had spread from the Near East to South Asia by fifty thousand years ago, and on to Australia by forty thousand years ago, Homo sapiens for the first time colonizing territory never reached by Homo erectus.

It has been estimated that from a population of two thousand to five thousand individuals in Africa, only a small group, possibly as few as one hundred and fifty to one thousand people, crossed the Red Sea.

Of all the lineages present in Africa only the female descendants of one lineage, mtDNA haplogroup L3, are found outside Africa.

Had there been several migrations one would expect descendants of more than one lineage to be found outside Africa.

L3's female descendants, the M and N haplogroup lineages, are found in very low frequencies in Africa (although haplogroup M1 is very ancient and diversified in North and Northeast Africa) and appear to be recent arrivals.

A possible explanation is that these mutations occurred in East Africa shortly before the exodus and, by the founder effect, became the dominant haplogroups after the exodus from Africa.

Alternatively, the mutations may have arisen shortly after the exodus from Africa.

Some genetic evidence points to migrations out of Africa along two routes.

However, other studies suggest that only a few people left Africa in a single migration that went on to populate the rest of the world, based in the fact that only descents of L3 are found outside Africa.

From that settlement, some others point to the possibility of several waves of expansion.

South Asia (49,293 – 28,578 BCE): Upper Pleistocene I — Loess Terraces, Rock Shelters, and Monsoon Pathways

Geographic & Environmental Context

During the late Pleistocene, South Asia was shaped by the contrasts of a weakened monsoon, extensive river terraces, and broad, exposed coastal plains.
The subcontinent spanned two dynamic realms:

• Upper South Asia: From the Hindu Kush–Karakoram–Himalaya and Indus–Ganga–Brahmaputra basins to the Siwalik and Terai foothills. Here, braided rivers sculpted loess-covered terraces, and glaciers capped the higher Himalaya.

• Maritime South Asia: The Deccan Peninsula and Sri Lanka—a world of rock shelters, tropical forests, and widened shelf coasts, joined intermittently by land bridges across the Palk Strait.

Together these landscapes supported highly mobile foragers who tracked monsoon pulses between upland caves, plains rivers, and coastal lagoons.

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Climate & Environmental Shifts

The epoch unfolded under glacial–interglacial oscillations that reshaped both monsoon and river regimes:

• Cool, dry glacial intervals weakened the Indian summer monsoon; winter westerlies dominated northwest India and the Himalayan forelands.

• Interstadials briefly restored humidity, recharging lakes and river discharge across the Ganga–Yamuna and Brahmaputra systems.

• Expanding glaciers in the Karakoram and Greater Himalaya coincided with broad Indus and Ganga terracesbuilt under fluctuating discharge.

• Peninsular India and Sri Lanka saw contraction of rainforests and expansion of deciduous woodland and savanna under reduced precipitation.

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Subsistence & Settlement

Upper South Asia

• Settlement Patterns:
  Seasonal mobility between mountain caves (Swat, Kashmir), Siwalik rock shelters, and riverine terraces along the Indus and Ganga plains.

• Diet and Hunting:
  Herd-following economies targeting wild equids, aurochs, nilgai, blackbuck, ibex, markhor, and red deer. River and oxbow habitats supplied fish and waterfowl during interstadials.

• Habitation Evidence:
  Caves and open-air hearths in Gandhara, the Rohri chert zone, and the Ganga–Yamuna Doab show continuity from Middle to Upper Paleolithic phases.

Maritime South Asia

• Rock-Shelter Foragers:
  Occupations at Kurnool, Jurreru, and other Deccan sites, where microlithic toolkits indicate long continuity of human presence.

• Coastal Economies:
  As sea level fell, broad shelf plains opened along the Konkan–Malabar–Coromandel coasts; foragers gathered shellfish, fish, crabs, and turtles on tidal flats.

• Sri Lanka’s Balangoda Culture:
  Hunter–gatherers at Fa-Hien Lena and Batadomba-lenā exploited rainforest mammals (monkeys, porcupine), freshwater fish, and yams, marking one of the world’s earliest successful tropical rainforest adaptations.

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Technology & Material Culture

• Stone Industries:
  Blade–flake and geometric microlithic traditions in both northern and southern India mark the full establishment of an Upper Paleolithic trajectory. Rohri chert quarries (Sindh) became major lithic source zones.

• Organic Technologies:
  Bone points, eyed needles, and hafted scrapers reflect tailored clothing and woodworking. Digging sticks and hammerstones aided tuber extraction and nut cracking.

• Symbolism and Ornament:
  Ochre for body paint or adhesive; perforated beads and pendants appear in late-phase contexts.

• Fire and Cooking:
  Structured hearths and roasting pits in caves and dunes suggest deliberate heat control for cooking and toolmaking.

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Movement & Interaction Corridors

• Northwest Passes: Khyber, Kurram, and Bolan gateways linked the Indus basin with Iranian and Central Asian plateaus.

• River Pathways:  Indus, Ganga–Yamuna, and Brahmaputra terraces served as highways for seasonal migration and exchange.

• Foothill Routes: Siwalik and Terai corridors connected Himalayan uplands to fertile plains.

• Peninsular Arteries: Godavari–Krishna–Tungabhadra valleys, Palghat and Palakkad gaps across the Western Ghats, and the Palk Strait (often a dry bridge) tied peninsular India to Sri Lanka and beyond.

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Cultural & Symbolic Expressions

• Ritual & Art:
  Hearth renewals, engraved bones, and faunal motifs from northern caves reflect animistic and ritual awareness. Early rock art in southern India (and ochred burials) suggests regional symbolism.

• Social Structure:
  Kin-based bands with cooperative foraging and shared tool production; roles in leadership and knowledge (e.g., hunting, healing, or navigation) were situational and seasonal.

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Environmental Adaptation & Resilience

• Mobility as Strategy: Alternation between upland shelters in cool dry months and river–delta plains during warmer seasons buffered against climatic unpredictability.

• Ecological Breadth: Combination of hunting, fishing, and plant foraging provided resilience through monsoon weakening.

• Technological Flexibility: Microblade composites and hafted multipurpose tools allowed rapid adaptation to varied ecologies—from the Thar scrub to the Deccan forests.

• Maritime Awareness: Knowledge of tidal rhythms and coastal resource scheduling foreshadowed the later Holocene seafaring and shell-working traditions of peninsular India and Sri Lanka.

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Transition Toward the Last Glacial Maximum

By 28,578 BCE, South Asia’s foragers had diversified into distinct but interconnected ecocultural systems:

• In the north, cold-adapted upland–river foragers navigated the loess plains beneath glaciated peaks.

• In the south, microlithic cave dwellers and coastal collectors exploited tropical forests and widening shelves.
  Both traditions thrived through technological ingenuity, mobility, and deep ecological knowledge—foundations that would carry them through the Last Glacial Maximum and into the Holocene’s emerging monsoon world.

Maritime South Asia 

(49,293 – 28,578 BCE) Upper Pleistocene I — Rock Shelters, Rainforest Foragers, and Shelf Coasts

Geographic and Environmental Context

Maritime South Asia includes Peninsular India south of the Narmada — Tamil Nadu, Kerala, Karnataka, Andhra Pradesh, Telangana, Maharashtra, Goa, Dadra & Nagar Haveli and Daman & Diu, southern Odisha, southern Chhattisgarh — plus Sri Lanka, Lakshadweep, the Maldives, and the Chagos Archipelago.

• Anchors: the Deccan (Godavari–Krishna–Tungabhadra–Kaveri basins), the Western/Eastern Ghats and Konkan–Malabar–Coromandel coasts, Sri Lanka’s wet/dry zones (Anuradhapura–Polonnaruwa heartlands), and the Lakshadweep–Maldives–Chagos atolls.

Climate & Environmental Shifts

• Cooler/drier glacial conditions; monsoon weakened; shelves widened along Konkan–Coromandel; Sri Lanka still connected intermittently to the mainland early, then increasingly insular.

Subsistence & Settlement

• Microlithic foragers in rock shelters (Kurnool, Jurreru valleys), dunes and tank-bed margins; coastal crews harvested shellfish/fish along widened shelves.

• Sri Lanka’s Balangoda culture exploited rainforest mammals, fish, and yams; cave sites (Fa-Hien Lena, Batadomba-lenā) show early modern human presence with microliths.

Technology & Material Culture

• Bladelets, geometric microliths; bone points; digging sticks; hafted scrapers; tailored garments.

• Ornaments and ochre in cave contexts.

Corridors

• Godavari–Krishna benches, Palghat and Palakkad gaps across the Ghats, Palk Strait land/raft links to Sri Lanka during lowstands.

Symbolism

• Rock art and ochred burials at select shelters; ritual treatment of prey.

Adaptation

• Coast–interior switching smoothed lean seasons; mixed woodland–savanna foraging.

Sri Lanka's earliest archaeological evidence of human colonization appears at the site of Balangoda, whose Mesolithic hunter gatherers arrived on the island about thirty-four thousand years ago and lived in caves, several of which have yielded many artifacts from these people, currently the first known inhabitants of the island.