From 1200 to 1450, the Indian Ocean was the center of world trade. Many different trade routes crossed its waves. They linked the South China Sea to the Indian Ocean to the Mediterranean Sea. Peoples and languages mixed in the great trading cities built on the Indian Ocean’s shores. Luxuries like Chinese porcelain and silk, East African gold and ivory, and Southeast Asian spices like cinnamon and nutmeg were in high demand far from where they were produced. These goods traveled thousands of miles from merchant to merchant and port to port. Their prices increased the further they traveled.

Indian Ocean winds

What made this remarkable trade possible? Wind. Specifically, the monsoon winds in the Indian Ocean. These winds changed direction twice a year in a predictable way. This allowed merchants to plan voyages and to know when they would arrive at a distant port. Travel guides written by Arab merchants listed ideal departure times, down to the best week and even day. Most merchants stayed relatively close to home. However, many Arab, Persian, and Indian merchants traveled as far as China. With so many merchants passing through, port cities became home to a highly varied mix of people from all over.

A network of ports

A network of merchants and trading cities developed as a result of all this trade. Connections formed between distant places, from Mozambique in East Africa to Hormuz on the Persian Gulf, Calicut in Western India, Malacca in Southeast Asia, and Quanzhou in China. Indian cities like Calicut (called Kozhikode in India; “Calicut” was the British corruption of the word) were the busiest ports in the Indian Ocean. They were situated at a half-way point between the western and eastern ends of the ocean. Merchants could use the monsoon winds to make a round trip to Calicut and back in a single year.

Religions and technologies traveled along with goods and people. Both helped extend trade. Hinduism, Buddhism, and Islam all spread to Southeast Asia. Merchants along the Swahili coast in East Africa brought Islam with them, winning many new converts. As Islam spread south, local Bantu languages, like Swahili, adopted several Arabic words. Many local languages began using the Arabic script.

The spread of trade sped up technological exchange. At the same time, technological inventions expanded trade. Merchants carried new plants and animals to new places, along with new agricultural methods. Arab merchants improved the astrolabe and developed the kamal, improving navigation (see images below). Chinese sailors improved the magnetic compass. Indian, Chinese, and Muslim shipbuilders upgraded ship designs, designing larger ships that could travel farther with more cargo.

A rising tide lifts all boats

The Indian Ocean might have been a world of trading cities, but the rise of several large empires helped drive the trade. In the years leading up to 1200, the Song Dynasty in China and several Islamic states in the western Indian Ocean brought stability to their regions. Their wealth encouraged trade. In addition, Chinese Song emperors gave more freedom to merchants.

The rise of the Mongol Empire in the thirteenth century expanded trade across Afro-Eurasia. The Mongols brought many regions under one imperial system. In the fourteenth century, the Black Death pandemic crippled overland trade. However, sea-based networks recovered quickly. The collapse of the Mongol Empire meant that overland trade was risky. Many merchants opted to avoid risk and trade on the sea routes.

But the most important factor driving Indian Ocean trade was not political or economic. It was cultural. The expansion of Islam helped connect distant parts of the system. Muslim merchants extended trade networks around the Indian Ocean. Those networks spread Islam to new places. Muslims paid lower taxes in states controlled by Muslim rulers. So, as Muslim states expanded to new places or local rulers converted to Islam, conversion had both religious and economic benefits. Merchants traveling to Muslim ports often converted to avoid taxes. Some who didn’t convert still adopted Muslim names to improve relations with Muslim states and merchants.

When they returned home, converts brought their new religion with them. Arabic became the common language of business throughout the Indian Ocean. Muslim merchants could travel across an ocean and meet other Muslim merchants who spoke the same language and had similar cultural values. Long-distance trade depended on trust. You had to trust the people transporting your goods to market. You had to trust that the currency you were paid had value. You had to trust that goods you bought were real. A shared language and set of beliefs improved trust between Muslim merchants.

The Admiral

The Islamic world reshaped trade networks. However, the most powerful state operating in the Indian Ocean was not Islamic, or even based in the Indian Ocean. That state was China, which was ruled by the Ming Dynasty after 1368. In the fourteenth and fifteenth centuries, Ming China developed the most advanced ship-building technology the world had ever seen. The Ming’s wealth and mighty ships gave them the opportunity to rule the Indian Ocean. But they chose a different route.

The greatest admiral in China was a Muslim Chinese man named Zheng He. From 1405 to 1433, he led seven expeditions of huge treasure fleets into the Indian Ocean. He sailed with hundreds of ships, but these weren’t your average sailboats. They were the largest ships in the world, some as large as 400 feet long. On his first voyage, he was accompanied by as many as 30,000 sailors. Each ship held dozens of cannons.

You might think the Ming emperor sent Zheng He on missions of conquest. However, the Chinese weren’t out to conquer or even to control Indian Ocean trade. Zheng He traveled to display the might of China and to collect tribute from rulers around the ocean. Many rulers paid their tributes happily.

Zheng He’s voyages highlight one of the most remarkable things about this Indian Ocean trade system: it was pretty peaceful. Of course, there were some wars. Pirates were a constant threat. Slavery was common in every region and was part of this trading system. Yet, no state in this period attempted to gain control over trade. Merchants were allowed to operate freely. As they traveled, they carried new goods and new ideas to the many ports they visited.