Answer: Invasion by Aksum
Step-by-step explanation:
Nubia was one of the better known empires of Africa by the Europeans due to its proximity to the ancient Egyptians. They were located to the south of Egypt in modern day Sudan.
Ruled on and off by the Egyptians, Greeks and the Romans, Nubia became the Kingdom of Kush. This Kingdom finally fell into decline when they were invaded from the south by the Ethiopian kingdom of Aksum after which three kingdoms took their place being Nobatia, Makuria and Alodia.