The fifth installation of the video game Europa Universalis (hereafter EU5) just came out, and it had some interesting economic modelling issues. However, to get to explanation of how EU5 relates to the historical period (the start date of the game is 1337) I first need to go back to the historical background of what the situation was like in 1337 in the lands of the Roman Empire. (Although EU5 is global, I am really only familiar with European/Mediterranean history of that era. The game systems...