Wanderlust World Wanderlust World In the late 15th century, Portuguese explorers (notably Diogo Cão, 1482–1484) sailed up the Congo River driven by the quest for the mythical Prester John—a legendary Christian priest-king believed to rule a vast, wealthy kingdom in the "Indies" (often placed in Africa or Asia). The Portuguese hoped to form an alliance against Islam and access trade routes. Instead, they encountered the Kongo Kingdom, establishing diplomatic and trade relations (including the tragic slave trade). The search for Prester John fueled much early Portuguese exploration of Africa's coast and interior.