The Monsoon Trade System: An Indian Ocean Network

Sometime before 100 B.C., Greek sailors coming from Egypt discovered a shortcut to India.  Much easier and more direct than the arduous overland route, or than hugging the deserted coastlines of Arabia and Persia for 5,000 miles, this route took only weeks to travel.  Sailing straight out into the open waters of the Arabian Sea during the late spring, ships were whisked by the monsoon winds on a steady northeast course, arriving on India’s west coast by mid-summer.

It was a daring feat for those first sailors who attempted it.  In a time when ships rarely ventured out of sight of land, and open waters invited the prospect of drifting aimlessly at sea, it took an extraordinarily bold, unlucky, or stupid navigator to sail out into one of the largest bodies of water on the planet.  Fortunately for those first crews who made the attempt, they were saved by one of the great forces of nature: the monsoon.

Highway Across the Ocean

The monsoon is a seasonal wind that reverses direction twice a year.  Starting in June, the Indian subcontinent heats up, creating a low-pressure system that draws cool, moist air from the southwest.  This produces a wind that blows steadily through the summer months and brings the rains that sustain India’s agriculture.

As the landmass cools off through the autumn, the cycle reverses itself.   From October to November, cool, dry air is drawn from the Himalayas and blow southeast across the Arabian Sea towards Africa.  This allowed merchants from the west to make a round-trip journey to India within a single year.  The same cycle operated over the Bay of Bengal to India’s east, ferrying traders to and from the islands of Southeast Asia.

Monsoon trade winds
Map of seasonal monsoon trade winds on the Indian Ocean: summer winds in red, winter in blue.

The route those early Greeks stumbled across had already been used for centuries by sailors traveling between India and East Africa, trading ivory and various metals.  As navigators from afar developed a large body of collective knowledge of winds and currents, a complex trading system evolved that spanned the entire Indian Ocean.

Merchants from Africa, Persia, India, and Southeast Asia, were able to count on this dependable wind to carry them on a round-trip journey every year.  Most often they sailed in small boats such as the famous dhow that contained no iron nails, but were sewn together with various plant fibers.  Despite traveling in these flimsy craft, mariners could use the steady and swift winds to traverse the ocean’s breadth in about the same time it took to sail the length of the Mediterranean, which was half the distance.

Overlapping Zones of Trade

Zanzibar's Stone Town, one of the major trade towns of Indian Ocean trade
Zanzibar’s Stone Town, a major port in Indian Ocean trade

Generally speaking, however, traders would not travel farther than a monsoon’s trip from their home port.  Greeks and Arabs ventured as far as western India; Indians ranged between the mouth of the Red Sea and the Malay Archipelago; Chinese and Southeast Asian merchants went as far as Sri Lanka.

Along these limits formed a string of emporia, where merchants speaking a babel of different languages would haggle and barter as part of the long process that brought goods from one extremity of the Indian Ocean to the other.  Ethiopians trading gold and ivory, Malays trading pepper and nutmeg, Yemenis trading frankincense and myrrh–all would mingle in trade towns and ports scattered across the ocean, negotiating the transshipment of their precious cargo in some common trade tongue.  Thus the silk that reached ancient Rome, or the spices that reached Europe before the age of colonization, would be handled by a multitude of merchants during a journey that could last years.

The Age of Colonialism

Painting of Vasco da Gama by António Manuel da Fonseca
Vasco da Gama

Once Portuguese explorers rounded the Cape of Good Hope, they began a campaign of conquest that subjugated Asia’s richest ports. The complex network that had defined Indian Ocean trade soon began to unravel.  Starting with Vasco da Gama in 1498, heavily-armed caravels rode the monsoon trade winds up from Africa to the west coast of India. They blasted through the defenses of local princes to commandeer their share of the lucrative spice trade.  Successive expeditions pushed further toward the point of origin of this valuable commodity, eventually setting up ports on the Spice Islands. With control of the source, they had a monopoly on the spice trade.

Portuguese hegemony did not last long, as armed merchant ships from Holland, France, and Great Britain soon arrived in the Indian Ocean with ambitions of their own.  Each of these powers, like Portugal before them, sought to bypass or co-opt the intricate chains of commerce that stretched across the ocean by creating mercantile zones in their conquered territories that excluded all foreign traders.  Over the course of a couple centuries, the trade system that endured for millennia was subsumed by European power politics. But the end of the monsoon trade system did not spell the end of monsoon trade.

Dhow on the Indian Ocean off Zanzibar
Dhow on the Indian Ocean off Zanzibar

Even after the age of steam replaced the age of sail, dhows plied the routes between East Africa and the Persian Gulf, carrying African ivory, spices from Yemen, and pearls from Abu Dhabi.  The seafaring habits that had persisted for millennia were slow to die off, only succumbing in the mid-20th century once the discovery of oil had permanently altered the economics of the region.  Massive supertankers replaced wooden boats as the flood of wealth into the Persian Gulf made it impossible to earn a living carrying small cargoes over thousands of miles.  The dhows that ferry tourists along the shores of Zanzibar and Dubai today are but a reminder of the great monsoon trade system that once spanned a whole ocean.


Want to learn more? Read:

A Splendid Exchange: How Trade Shaped the World: A history of global trade. One of those rare gems that goes into greater detail in older history than in modern.

Monsoon: The Indian Ocean and the Future of American Power: A discussion of the geopolitics of the Indian Ocean, going back in time up into the future.

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