Economics is everything.
The only (with the exception of the religion or "glory") reason to invade another country is to seize their land, their assets, and gain control of the tax-paying population. If the land has no people there, no town, no resources, no anything. No-one cares about it.
Just because marx and the modern definition of socialism didn't exist until 1453, doesn't mean that it never occurred before in history.
Rome failed because they ran out of money. We can debate WHY they ran out of money, but if they didn't have the expense of providing food, entertainment, and all the other benefits that they got, to the people of Rome they wouldn't have had to hyperinflate their currency to pay for it all.
(post is archived)