I read somewhere that the Roman Empire has not ended. It just morphed into the Catholic Church and has had various emanations(Austro-Hungarian empire) since then. One of the reason Christianity was chosen as the main religion was that it emphasized "turning the cheek" and followers already believed in one power, so it was thought that it would be easier to rule the masses this way.
Tangently Related: The Holy Roman Empire of the German Nation was the biggest mislabeling of human history - neither Holy, nor Roman, nor an Empire, not a Nation and not really German.
Gibon I think is where I got it from.