When Afonso I of Kongo was established the Roman Catholic Church in Kongo kingdom. By 1516 Afonso I sent various of his children and nobles to Europe to study, including his son Henrique Kinu a Mvemba, who was elevated to the status of bishop in 1518. Afonso I wrote a series of letters to the kings of Portugal Manuel I and João III of Portugal concerning to the behavior of the Portuguese in his country and their role in the developing slave trade, complaining of Portuguese complicity in purchasing illegally enslaved people and the connections between Afonso's men, Portuguese mercenaries in Kongo's service and the capture and sale of slaves by Portuguese.