Christian Europeans had already begun invading and colonizing lands outside of Europe before the Council of Constance, demonstrating how the Doctrine was applied to non-Christian Indigenous peoples outside Europe. In the 14th and 15th centuries, the Indigenous peoples of what are now referred to as the Canary Islands, known as Guanches (who had lived on the islands since the BCE era) became the subject of colonizers' attention. The Guanches had remained undisturbed and relatively 'forgotten' by Europeans until Portugal began surveying the island for potential settlement in 1341. In 1344, a papal bull was issued which assigned the islands to Castile, a kingdom in Spain. In 1402, the Spanish began efforts to invade and colonize the islands. By 1436, a new papal edict was issued by Pope Eugenius IV known as "Romanus Pontifex" which authorized Portugal to convert the Indigenous peoples to Christianity and control the islands on behalf of the pope. The Guanches resisted European invasion until the surrender of the Guanche kings of Tenerife to Spain in 1496. The invaders brought destruction and diseases to the Guanche people, whose identity and culture disappeared as a result.