How did the indian ocean affect trade in east africa

The Indian Ocean is one of the oldest trade routes between Africa and Asia. Indian Ocean trade was made easy by the monsoon winds that circulated between Asia and the Eastern coast. These winds blew north to the south and from the south back to the north in a circular fashion. It took the Arabs from Persia close to two months traveling to the eastern coast. Arabs who settled on the eastern coast and married members of the ruling class and traders also helped trade with the Arabs. 
Indian Ocean trade networks also helped in the birth of new kingdoms on the island of Madagascar. This trade made the Merina part of the Indian Ocean trade network, which covered the whole of the Indian Ocean continents and islands.