If I remember correctly, the Kingdom of Aksum (based out of Ethiopia and Eritrea) was the third largest empire in the world, and on par with Rome and Carthage in terms of advancement.

When they collapsed, they vanished, unlike the Roman empire, which culturally just kind of splintered off into the holy Roman empire, the franks, etc...

I often wonder what Africa would look like if something like the HRE replaced the aksumite empire.