How did medieval Arab and Persian sailors use monsoon winds to cross the Arabian Sea?

From the 8th or 9th century onward, Arab and Persian seafarers mastered the navigation of the Arabian Sea by utilizing surface currents propelled by seasonal monsoon winds. By aligning their voyages with these predictable wind patterns, sailors were able to cross the sea efficiently between ports in southern Arabia, East Africa, India, Malaysia, and China.1

To facilitate these journeys, pilots from regions such as Oman and the Hadhramaut documented detailed navigational instructions in works known as rahmangs (books of routes). These manuals provided essential guidance on:1

• Environmental conditions: Descriptions of winds, currents, and soundings.1
• Navigation: Techniques for using the stars to maintain course.1
• Geography: Detailed information regarding coastlines, approaches, and landmarks, such as Cape al-Hadd and Cape Gwardafuy.1

This sophisticated understanding of the Indian Ocean wind systems allowed medieval mariners to maintain flourishing trade networks, connecting major hubs like Muscat, Aden, and various Indian ports.1