How were past times so violent?

[Mr Greene]

Noting that there was a medieval agricultural revolution is not to say that this revolution occurred out of a vacuum.  Pre med warm period ag and post med warm period ag are fundamentally different - with what came after being the basis of modern ag.  Villas did not possess the needs, the tools, or the management principles - so this shouldn't be taken as a criticism of that system either.  

Just a credit where credit is due thing.  Huge swaths of the world might have been covered in a feudal morass, and those serfs who worked the land were at the bottom of the social order...but they did produce an innovative agricultural system that we use to this day.  It was a significant achievement for humanity.

The bread basket of the Roman Empire was the former Carthaginian Empire. The tools and know how were there whether or not the European villas chose to take advantage of them. Of course once the Empire started going to **** they imported the tools and methods (adapted for local circumstances). 
Carthage of course always existed on a precarious position, and was able to develop it's agriculture by drawing from a glacial aquifer. Of course they eventually drained it producing the largest desert on the planet...