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
Time in Portugal re-introduced, it could never be observed as CEST (), and the only solution was to re-adopt WET as standard time. So, in 1976, Portugal adopted WET () as its standard time. DST started to be observed every year as WEST () usually from early April to later September. From 1981 on, DST started to be observed from the last Sunday in March to the last Sunday in September. In 1986, time in Portugal began to be calculated in accordance with UTC, instead of GMT.<ref name="Decree-Law 44-B/86"> Decree-Law 44-B/86, 7 March 1986 (in Portuguese). Retrieved 19 May 2013.</ref> In 1992, during