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Treaty of Tordesillas (1494)

Christopher Columbus 's 1492 discovery for Spain of the New World, which he believed to be Asia, led to disputes between the Spanish and the Portuguese. These were eventually settled by the Treaty of Tordesillas in 1494, which divided the world outside of Europe in an exclusive duopoly between the Portuguese and the Spanish along a north–south meridian 370 leagues, or 970 miles (1,560 km), west of the Cape Verde islands. However, as it was not possible at the time to correctly measure longitude, the exact boundary was disputed by the two countries until 1777.

The completion of these negotiations with Spain is one of several reasons proposed by historians for why it took nine years for the Portuguese to follow up on Dias's voyage to the Cape of Good Hope, though it has also been speculated that other voyages were in fact taking place in secret during this time. Whether or not this was the case, the long-standing Portuguese goal of finding a sea route to Asia was finally achieved in a ground-breaking voyage commanded by Vasco da Gama.