Answer: Monsoons.
Step-by-step explanation:
Navigators that had already traveled between India and East Africa, exchanging ivory and different metals, developed a vast selection of collective knowledge of winds and currents to develop a trading system that crossed the entire Indian Ocean.
Merchants from Africa, Persia, India, and Southeast Asia, depended on the wind to carry their ships on their journeys every year. They used the winds to cross the ocean’s vastness in record time.