"France and "Rome" are hardly in the same category."
No, the Roman Empire that extended throughout Europe was brought to its knees over time by barbarians from within its borders. The same can be said about France and Europe in general, though I'm not saying the Chirac's government is about to be toppled any time soon.
In 538 AD the Western Roman Empire went down for the last time. The Dark Ages began that spring, and lasted, more or less, for another millenium. The Eastern Roman Empire stayed in business.