The papal bull Inter caetera was a significant decree issued by Pope Alexander VI, aiming to address and alleviate tensions between Spain and Portugal regarding their claims to newly discovered lands in the New World. Following Christopher Columbus’s voyages and the opening of new territories, both nations sought to expand their influence and territory in the Americas. The pope, recognizing the potential for conflict, issued this document to establish a clear division of the New World between the two powers. The bull defined a Line of Demarcation, which effectively divided the Americas into Spanish and Portuguese territories and was aimed at promoting peace between the rival nations.

The Line of Demarcation, as outlined in Inter caetera, extended from the North to the South Pole, with lands to the west belonging to Spain and those to the east to Portugal. This demarcation was critical because it influenced the trajectory of exploration and colonization in the following centuries. Both nations were granted rights to conquer and convert indigenous peoples, significantly impacting their cultures and lives. The papal bull was later complemented by the Treaty of Tordesillas in which the two nations adjusted the line further west, while the initial bull emphasized the Catholic Church's authority over international matters of land and exploration.

This division not only fulfilled the immediate needs of Spain and Portugal but also set a precedent for European colonial practices and the role of papal authority in geopolitical matters. The Inter caetera was rooted in the religious fervor of the time, emphasizing Catholicism as a unifying force in European exploration. However, the awarded rights led to exploitation and colonization that had lasting consequences on native populations, cultures, and the geopolitical landscape of the Americas as a whole in subsequent years.