In response to earlier vague bulls issued by the popes to formalize the Portuguese expansion into Africa and the Spanish claims on the Americas, Portugal and Castile signed the Treaty of Tordesillas between themselves in 1494, agreeing to respect each anothers' monopolies in the newly discovered areas.

Learning the secret location of the "spice islands"—the Bandas and Ternate and Tidore in the Malukus in present-day Indonesia, then the single source of nutmeg and cloves and the main purpose for the European exploration of the Indian Ocean[citation needed]—Albuquerque sent an expedition there under António de Abreu.

Each crown appointed three astronomers and cartographers, three pilots and three mathematicians, who formed a committee to establish the exact location of the antimeridian of Tordesillas, and the intention was to divide the whole world into two equal hemispheres.

According to contemporary Castilian writer Peter Martyr d'Anghiera, a small boy stopped the Portuguese delegation and asked if they intended to divide up the world.

Geographic knowledge at that time was inadequate for an accurate assignment of longitude, and each group chose maps or globes that showed the islands to be in their own hemisphere.

[9] In 1526 Jorge de Meneses reached northwestern Papua New Guinea, landing in Biak in the Schouten Islands, and from there he sailed to Waigeo on the Bird's Head Peninsula.

It was in the interests of the emperor to avoid conflict, so that he could focus on his European policy, and the Spaniards did not know then how to get spices from the Maluku Islands to Europe via the eastern route.

The Treaty of Zaragoza laid down that the eastern border between the two domain zones was 297+1⁄2 leagues (1,763 kilometres, 952 nautical miles)[note 4], or 17° east, of the Maluku Islands.

The treaty included a safeguard clause which stated that the deal would be undone if at any time the emperor wished to revoke it, with the Portuguese being reimbursed the money they had to pay, and each nation "will have the right and the action as that is now."

That never happened, however, because the emperor desperately needed the Portuguese money to finance the War of the League of Cognac against his archrival Francis I of France.

[12] Under the treaty, Portugal gained control of all lands and seas west of the line, including all of Asia and its neighbouring islands so far "discovered", leaving Spain with most of the Pacific Ocean.