With the decline of the Roman Empire, China had become a main focus of trade in the Indian Ocean. The Chinese consumed enormous quantities of spices which were imported from South-East Asia and India. They also imported ivory, the best of which came from Africa, and glassware which came from West Asia.

To these were added medicinal herbs, lac, incense and all types of rare things. Generally products from Africa and West Asia did not go beyond the Malabar in South India. Nor did Chinese ships go beyond the Moluccas in South-East Asia.

Thus both India and South-East Asia were important staging centres for trade between China and the countries of West Asia and Africa. Indian traders, especially the Tamil and Kalinga from modern Orissa and Bengal, played an active role in this trade, along with Persians and later Arabs.

Much of the trade to China was carried in Indian ships, the teak-wood of Malabar, Bengal and Burma providing the base of a strong tradition of shipbuilding. The weather conditions were also such that it was not possible for a ship to sail straight from the Middle East to China. The ships would have to wait for a long period in ports in between for favourable winds, which blow from the west to the east before the monsoon and from east to west after the monsoon.