I’ve gone through a lot of the old titles and the short answer is: it’s a rough sketch of history, not a textbook. The timelines, tech trees and even the general feel of a Roman legion versus a Mongol horde line up with what we know, but the developers had to compress centuries into a few hundred hours of play. Cities pop up where they shouldn’t, cultures get lumped together, and a few techs are anachronistic just to make the game interesting. So if you’re looking for a realistic simulation, it’s good for getting the broad strokes, but don’t expect it to be a flawless historical replica.