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 March to last Sunday in October in the whole country.<ref name="Regional Legislative Decree 6/96/M"> Regional Legislative Decree 6/96/M (Madeira), 25 June 1996 (in Portuguese). Retrieved 26 May 2013.</ref><ref name="Regional Legislative Decree 16/96/A"> Regional Legislative Decree 16/96/A (Azores), 1 August 1996 (in Portuguese). Retrieved 26 May 2013.</ref> In 1996 Portugal adopted ISO 8601 via EN 28601 as NP EN 28601:1996. The Astronomical Observatory of Lisbon publishes the official time via the Network Time Protocol (NTP), e.g. via "ntp02.oal.ul.pt" and "ntp04.oal.ul.pt". The IANA time zone database contains 3 zones for Portugal. Columns marked with * are from the file zone.tab from the