A King of Kongo ends up actually marrying into the Portuguese royal family very early on in Portuguese-Kongo contact. As a dowry, the king asks for a small armada of ships, ostensibly so that his bride could go to Europe whenever she needed. In actuality, the ships are used as prototypes for Kongolese naval expansion; this is bolstered as more powerful interior kingdoms begin to pick apart the peripheral portions of the Kongo. Within a few decades, Kongo works out the kinks of making successful naval vessels out of wood that grew in the area, and thus begins to expand it's influence. Furthermore, a King of the Kongo, perhaps motivated by the population loss in the interior and partially to ward off European "offers," bans the foreign sale of slaves (Individual African kingdoms banning slavery has several historical precedents and Europe for the most part left them alone). At the same time, Portugal ends up settling more in South Africa rather than in Mozambique or Angola, and thus ends up relying more on India and China for slavers rather than Africa. Kongo becomes something of a regional power and perhaps even attempts to set up a handful of colonies on their own, though the Pope would be generally wary of granting colonial charters.