What 1529 treaty fixed Spain and Portugal's boundary claims in Asia?

The 1529 treaty that fixed Spain and Portugal’s competing boundary claims in Asia was the Treaty of Zaragoza.

Signed on 22 April 1529 in Zaragoza, the agreement addressed the unresolved eastern counterpart to the 1494 Treaty of Tordesillas. Tordesillas had divided claimed overseas spheres along a meridian in the Atlantic, but the first circumnavigation made the location of the opposite side of the world strategically important. Both monarchies claimed the valuable Spice Islands, or Moluccas.

Zaragoza established an antimeridian in the Pacific region and assigned the Moluccas to Portugal. Emperor Charles V, who ruled Spain’s Habsburg territories, accepted a payment of 350,000 ducats in return for renouncing his immediate claim to the islands. The treaty therefore helped prevent a direct Spanish-Portuguese conflict over the spice trade.

It is often confused with Tordesillas. Tordesillas dealt primarily with the Atlantic division agreed in 1494; Zaragoza dealt with the corresponding Asian boundary in 1529. Spain later maintained a major presence in the Philippines, showing that the practical application of the boundary remained politically complicated.