Supervised by Spanish-born Pope Alexander VI; the Treaty of Tordesillas in 1494 divided the world in half鈥攊nto Spanish and Portuguese territories. However; following Portugal's discovery of the Spice Islands of the Moluccas in 1512; Spain contested the line of demarcation. The issue was never fully settled; but the Treaty of Zaragoza in 1529 attempted to resolve the matter by setting the 鈥榓ntemeridian' as 17 degrees to the east of the Moluccas; thus preventing the Spanish from claiming the Spice Islands.

This 1522 map favors the Spanish claim; with the antemeridian cutting through Siam; Malacca and Sumatra; hundreds of miles west of the Moluccas.