The climate of South Asia is largely controlled by seasonal monsoon winds and rainfall patterns. During the summer, moist winds from the ocean blow inland, bringing heavy rains that are critical for agriculture but can also cause damaging floods. The monsoon rains were celebrated in ancient Indian poetry and provided the water necessary for crops, but also posed risks if the rains were too heavy or came at the wrong times. The monsoon winds further influenced trade and cultural exchanges, as sailors used the summer winds to reach South Asian ports and then waited for the winter winds to return them to their homelands.