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
Brouwer Route that there was no accurate way at the time to determine longitude. The sighting of either Amsterdam Island or Saint Paul Island was the cue for ships to change direction and head north. However, this was reliant on the captain's expertise. The route was devised by the Dutch sea explorer Hendrik Brouwer in 1611, and found to halve the duration of the journey from Europe to Java, compared to the previous Arab and Portuguese monsoon route, which involved following the coast of East Africa northwards, sailing through the Mozambique Channel and then across the Indian Ocean, sometimes via India. By