Around 1312 Genoese navigator Lancelotto Malocello came upon the Canary Islands. The Portuguese travelled there in 1341 both to trade and raid. By 1346 slave raiding was occurring. However, the first attempt at permanent colonization was sponsored by the Castilians in 1402. During the 14th century, a variety of forces competed for control of the Canaries: Genoese, Catalan-Mallorcan, Castilian, and Portuguese. In the following century, Castile and Portugal were the primary contenders.
In the early 15th century the Portuguese searched for a sea route to India to participate in the spice trade. As a first step, Prince Henry the Navigator launched expeditions to explore the West Coast of Africa. This experience, exerted a deep impression so that his reign later on was marked by an ambitious expansion that resulted to exploratory achievements. This, however, led to disputes between the Portuguese and the Castilians regarding control along the African coast. As an independent third party, the Pope would, on occasion, be asked to arbitrate disputes between kingdoms. On January 5, 1443, in the papal bull Rex regum, Eugenius IV took a neutral position on the disputed claims of Castile and Portugal over territory in Africa, which both claimed.