Final answer:
The Spanish occupation of the Philippines was based on the 1529 Treaty of Zaragoza, which resolved a conflict with Portugal over Eastern territories, assigning the Philippines to Spain and establishing it as an important base for its Asian trade, especially after the discovery of silver in the Americas.
Step-by-step explanation:
The Basis for Spanish Occupation of the Philippines
The initial basis for the Spanish Crown's occupation of the Philippines in 1521 was driven by geopolitical and economic interests following the age of exploration. Spain, through the Treaty of Tordesillas, was granted authority over new territories to the west of a meridian line. However, the exact demarcation of the zone of influence in the Eastern Hemisphere was unclear. This led to the conflict between Spain and Portugal over the Moluccas, or Spice Islands, which were highly coveted for their valuable spices. Although Ferdinand Magellan, sailing under the Spanish flag, reached the Philippines and claimed them for Spain, it was not until the Treaty of Zaragoza in 1529 that the dispute was settled.
The treaty gave the Moluccas to Portugal and the Philippines to Spain. Even though the Spanish were initially disappointed not to have access to the Spice Islands, they found silver in their American colonies, which soon made the Philippines an important base for Asian trade and the galleon trade route. The occupation was cemented by strategic trade interests, particularly in silver, and the Philippines' importance grew as a key center in Spain's expansive trade network in Asia.