I read the Dark Herald from time to time for both his reviews of coming movies and films and for his commentary about some of the important events of the day. In this one he gets into the consequences of a disaster of such massive and earth shaking proportion that its echoes shaped the world as we have known it for the last thousand years. It's interesting to me because there are certain similarities with modern day earth and the one that existed a thousand years ago.
His premise is pretty simple. Throughout written history all civilizations were static. Nothing ever really changed all that much because once a food supply was assured it made little difference if the people who fought did the fighting with stone age weapons, bronze or iron weapons. Egypt and China remained essentially static and unchanged for thousands of years and Europe was trapped in the same bubble until the Black Death wiped out two thirds of the population in Europe and things CHANGED.
Anyway, read the link. It won't take long.