Civilization-Destroying Catastrophe

This is from a thread I put up in World-Building: I figured it could work here, though, and I'd probably get more responses too.

All right, in a fantasy story I'm writing, the backstory features a Magitek civilization on a Crystal Spires and Togas level, and a disastrous series of events results in the complete annihilation of this civilization, to the point that a full rebuild would be impossible. This catastrophe results in the southern half of the empire's former dominion becoming completely uninhabitable, save for dangerously mutated creatures that lie within the area; the northern half, on the other hand, is able to get back on its feet and develop working (though not friendly) countries and civilizations after some time, though none are on the same level as the old one. The question I have is, just how long would it take for a civilization about the size of the United States to recover from an apocalyptic event like this, to about an early Age Of Exploration- Late Middle Ages level of civilization?

The level of technology present is futuristic, though not of the same nature as Sci-Fi, since magical research has replaced what we would consider scientific research in its importance. The disaster would be similar to a large scale nuclear meltdown blanketing the entire southern half of the United States, and the Magitek was completely reliant on the destroyed magical artifact, which was one of a kind and could not be replicated by any process they had yet discovered. Magitek was still possible, but it could not be produced to the same scale as it had been during the time of this civilization.

edited 6th Sep '11 10:14:55 PM by tropetown

Too many variables and fantastic elements to actually base this on historical fact (like the Fall of Rome and the Renaissance), but I'd say nobody could complain about anything between seven-hundred to one-thousand years.

Seven hundred to a thousand years was what I was leaning towards. There could still be a parallel comparison, as the technology played a major role in the operation of this civilization, however, and the effects of the sudden removal of such a key part of day-to-day life, coupled with civil war, and the destruction of the most fertile, densely populated region could still be imagined.

edited 7th Sep '11 8:46:39 AM by tropetown