The Treaty of Response area was an agreement between Spain and Portugal that established the Line of Response area. This line divided the region and led to the colonization of South America.

The treaty was signed in 1494 and was mediated by the Pope, with the intention of reducing conflict between the two European powers over their territorial claims in the New World. The Line of Response area was drawn from north to south, 370 leagues west of the Cape Verde Islands, dividing the undiscovered lands between Spain and Portugal.

Spain was granted control over all lands to the west of the line, while Portugal was granted control over lands to the east of the line. This division eventually led to the colonization of South America, with Spain claiming most of the continent and Portugal claiming parts of modern-day Brazil.

The Treaty of Response area was a significant moment in the history of European colonization, as it helped to prevent direct conflict between Spain and Portugal while also shaping the future territorial divisions in the Americas.