Indian Monsoon Current

Across the northern Indian Ocean, seasonal monsoons reverse both the prevailing winds and important surface currents. South of Sri Lanka, the summer current carries Arabian Sea water eastward towards the Bay of Bengal; the winter flow runs in the opposite direction. For sailing communities, these changing conditions formed part of a practical body of knowledge about routes, seasons and landfalls.

During the fifteenth and sixteenth centuries, Indian Ocean pilots recorded that knowledge in navigational writings. Ahmad ibn Majid composed numerous works in verse and prose, while Sulayman al-Mahri continued the tradition. Their expertise combined astronomical observation with experience of coasts and open-water crossings. When Portuguese ships entered the ocean at the end of the fifteenth century, they depended on pilots already familiar with its waters. Such encounters brought different navigational traditions into contact. The history of the monsoon seas therefore includes both recurrent environmental change and the transmission of specialist knowledge, through which sailors connected distant ports without relying on a single continuous coastal route.