I see

Yeah it took at least a century.

It went from a superpower to fragmented pretty freaking fast. It took awhile for those fragments to erode. What is crazy is that they survived multiple insane leaders. The fall of Rome isn't exactly due to an Emperor, it was a 3 front war and unsustainable resource consumption. Did you know the Romans created the Sahara Desert? There used to be a forest along the coast of Northern Africa, protecting the soil from the winds and allowing mountain springs to feed plains across the Sahara. The Romans chopped down that entire forest and well... yeah. This also screwed up the early Amazonians and is half the reason the amazon rain-forest got so freaking big.