Sometime 1482-83 the Portuguese navigator Diogo Cão became the first European to reach the kingdom of Kongo (Wikipedia: Kingdom of Kongo). The Portuguese had an active presence in the region until 1975. Following Oliver and Atmore (2001) I call the early part of this period, 1250-1800, “Medieval Africa”
Oliver, R. & Atmore, A. (2001). Medieval Africa, 1250-1800. Cambridge University Press.