As Portugal expanded southward into North Africa in the 15th century, new edicts were added by subsequent popes which extended Portuguese authority over Indigenous peoples. In 1455, Pope Nicholas V re-issued the "Romanus Pontifex" with more direct language, authorizing Portugal "to invade, search out, capture, vanquish, and subdue all Saracens and pagans" as well as allowing non-Christians to be placed in slavery and have their property stolen. As stated by Robert J. Miller, Jacinta Ruru, Larissa Behrendt, and Tracey Lindberg, the doctrine developed over time "to justify the domination of non-Christian, non-European peoples and the confiscations of their lands and rights." Because Portugal was granted 'permissions' by the papacy to expand in Africa, Spain was urged to move westward across the Atlantic Ocean, searching to convert and conquer Indigenous peoples in what they would understand as the 'New World.' This division of the world between Spain and Portugal was formalized with the Treaty of Tordesillas in 1494.