Indian Ocean trade Madagascar at this time leaving behind a lasting cultural and genetic legacy. Chinese fleets under Zheng He criscrossed the Indian Ocean during the early part of the 15th century. The missions were diplomatic rather than commercial, but many exchanges of gift and produces were made. The Portuguese under Vasco da Gama discovered a naval route to the Indian Ocean through the southern tip of Africa in 1497–98. Initially, the Portuguese were mainly active in Calicut, but the northern region of Gujarat was even more important for trade, and an essential intermediary in east-west trade. Venetian interests were directly threatened as
Ottoman naval expeditions in the Indian Ocean against Portuguese attacks. In 1534, Suleiman annexed most of Iraq and by 1538 the Ottomans had reached Basra, i.e., the Persian Gulf. The Ottoman Empire still faced the problem of Portuguese controlled coasts. Most coastal towns on the Arabian Peninsula were either Portuguese ports or Portuguese vassals. Another reason for Turco-Portugal rivalry was economic. In the 15th century, the main trade routes from the Far East to Europe, the so-called spice route, was via the Red Sea and Egypt. But after Africa was circumnavigated the trade income was decreasing. While the Ottoman Empire was a major sea power in the