Nkuwu Nzinga, the ruler of the Kingdom of Kongo, was baptised as João I by Portuguese missionaries.

The Kingdom of Kongo was a kingdom in Central Africa. It was located in present-day northern Angola, the western portion of the Democratic Republic of the Congo, southern Gabon and the Republic of the Congo. At its greatest extent it reached from the Atlantic Ocean in the west to the Kwango River in the east, and from the Congo River in the north to the Kwanza River in the south. The kingdom consisted of several core provinces ruled by the Manikongo, the Portuguese version of the Kongo title Mwene Kongo, meaning "lord or ruler of the Kongo kingdom", and its sphere of influence extended to neighbouring kingdoms, such as Ngoyo, Kakongo, Loango, Ndongo, and Matamba, the latter two located in what became Angola.

King João I was the 5th ManiKongo of the Kingdom of Kongo between 1470 and 1509. He voluntarily converted to Catholicism. He was baptized on 3 May 1491 and took the Christian name of João. Soon after, ManiKongo Nzinga-a-Nkuwu João I abandoned the new faith for a number of reasons, one of them being the Catholic Church's requirement of monogamy. Politically, he could not afford to abandon polygamy and embrace monogamy, a cultural shift that the king could not contemplate as power in Kongo was elective, rather than hereditary as in Europe; as Kongo culture followed a matrilineality structure, where the elder son of the king is not automatically the next king.