By 1400, innovations in maritime navigation and technology, and political instability in the Asian heartland had combined to shift the focus of long-distance Old World commerce from the overland caravan routes of the Mongolian steppes to ocean travel. The sea lanes and trading centres linking Europe and the Islamic West with the eastern extremities of the Old World had evolved into an elaborate and well-defined trading zone focussed on the Indian Ocean and the South China Sea. The zone was "ecumenical" in the sense that it incorporated a polyglot assortment of traders of many different cultural backgrounds. Not all cultural groups got along well together, but until the Portuguese entered the region at the beginning of the 16th century, rivalries and dissension rarely erupted into open conflict. Foreign merchants from the Islamic, Indic, Chinese and Southeast Asian regions all plied the sea lanes with trade goods, and congregated in coastal port communities to buy and sell merchandise.

Map of Portugal's Ecumenical Trade Zone

Trading centres dotted shorelines from China and Indochina to east Africa and the Arabian coast. Sailing through the South China Sea, mariners could conduct business at ports in Borneo, the Philippines, Java, Sumatra, and the Malay Peninsula. Few traders travelled the entire trade circuit. The Chinese, for example, rarely ventured west of the Strait of Malacca after 1433. Indian and Middle Eastern merchants sailed the Bay of Bengal and the Indian Ocean, stopping at ports in Ceylon, on India's Malabar Coast, and on the Arabian and East African coasts.

Anchoring the trade network were key cities in stable empires like Canton, in China, regional states like Cambay, and city-states like Malacca and Aden. Each funnelled goods in and out of local and regional trading areas, and linked the sea routes to long-distance inland caravan roads.

Arab traders dominated the trade network west of the Strait of Malacca, and Chinese rules and customs prevailed to the East. However, entry into what amounted to a trade "club" was open to everyone provided they abided by the established rules of the enterprise. The price of entry was a fee for protection against attacks from pirates, who maintained thriving enterprises throughout the area.

In each port centre within the ecumenical zone, traders would find banking facilities, secure warehouses for their goods, prescribed methods for establishing market prices, and residential quarters which in all likelihood housed people of their own cultural background. For example, Ethiopians arriving in 15th century Calicut, focus of the Indian Ocean segment of the trade network, would have found resident countrymen in the local merchant community.

Banking Facilities - The Cheque

The local cultures of the urban centres in the ecumenical trading sphere, and the cultural mix in the various trade communities differed substantially. At the western periphery of the zone, Italians, Greeks, Jews, and Muslims mingled in Alexandria. At the juncture of the Indian Ocean and South China Sea, Chinese, Indic and Southeast Asian traders conducted business in Malacca and Palembang. However, a merchant arriving in any of these ports would have recognised the structure of the local trade community, and the rules of acceptable commercial conduct.