In 1493, the Spanish rulers asked for papal support for their claims to the New World discovered by Columbus, in order to restrain the Portuguese and other potential rival claimants.
Pope Alexander VI established an imaginary line running north and south through the mid-Atlantic, 100 leagues (480 km) from the Cape Verde islands. Spain would have possession of any unclaimed territories to the west of the line and Portugal would have possession of any unclaimed territory to the east of the line.
Spanish and Portuguese ambassadors reaffirmed the papal division, but the line itself was moved to 370 leagues (1,185 miles) west of the Cape Verde Islands, or about 46°30′ W of Greenwich.
