[Verginius Rufus]

I once heard Pope Shenouda (head of the Coptic Church) give a talk (in the US).

The Christians of North Africa (present-day Tunisia-Algeria-Morocco) eventually disappeared, but I think it was not until much later (era of the Crusades) that they disappeared entirely. St. Louis IX of France died in Tunisia in 1270 while on a Crusade...it may have been even later than that that the native Christian population disappeared.

[muawiyah]

You have to recall that much of Christianity in North Africa had deteriorated into individual hermit monks wandering about the North African wilderness.

Although the ecological/climatic disaster that precipitated the Dark Ages didn't make North Africa unliveable, it pretty much kicked civilization there in the teeth for many centuries.

Spain ended up being the high spot in the West and attracted everybody worth knowing.