It is known that in the past, sailing ships transported goods from East Africa to Asia only in the summer and returned

It is known that in the past, sailing ships transported goods from East Africa to Asia only in the summer and returned in the winter, explain why this happened.

The reason for this was strong winds – monsoons, which change their direction depending on the season. In general, this phenomenon is typical for the equatorial zones, where in the summer period the winds are directed towards the land, and in the winter – towards the ocean.
In the Indian Ocean, in summer, monsoons blow towards the Indian subcontinent, and in winter – towards the African coast.
If we neglect the seasonality of the monsoons, the sailing ship will have to contend with an intense headwind, and the duration and difficulty of sailing will increase significantly.