Final answer:
The Treaty of Tordesillas established the division of new territories between Spain and Portugal by defining zones of exploration rights in the Americas, thereby shaping the future colonial structure in the region.
Step-by-step explanation:
The Treaty of Tordesillas, signed in 1494, established the boundaries of Spanish and Portuguese exploration rights in the Americas. This agreement was made to prevent conflict between Spain and Portugal as they sought new trade routes and territories following Columbus's voyage in 1492. The treaty specified a meridian 370 leagues west of the Cape Verde Islands, with territories to the west of this line reserved for Spain and those to the east for Portugal. When Pedro Álvares Cabral landed on the eastern coast of South America in 1500, he could claim it for Portugal due to the Treaty of Tordesillas.