<P> In Madagascar, merchants and slave traders from the Middle East (Shirazi Persians, Omani Arabs, Arabized Jews, accompanied by Bantus from southeast Africa) and from Asia (Gujarat Indians, Malays, Javanese, Bugis) were sometimes integrated within the indigenous Malagasy clans New waves of Austronesian migrants arrived in Madagascar at this time leaving behind a lasting cultural and genetic legacy . </P> <P> 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 . </P> <P> 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 . </P> <P> Venetian interests were directly threatened as the traditional trade patterns were eliminated and the Portuguese became able to undersell the Venetians in the spice trade in Europe . Venice broke diplomatic relations with Portugal and started to look at ways to counter its intervention in the Indian Ocean, sending an ambassador to the Egyptian court . Venice negotiated for Egyptian tariffs to be lowered to facilitate competition with the Portuguese, and suggested that "rapid and secret remedies" be taken against the Portuguese . The Mamluks sent a fleet in 1507 under Amir Husain Al - Kurdi, which would fight in the Battle of Chaul . </P>

How did european nations take control of the indian ocean trade zone