As I have been going through the game, learning different aspects, I confess that I never really bothered about Loyalty and even less about Ages. Sure it doesn't sound particularly nice to experience a Dark Age but it probably means those era scores missed are going to appear soon giving you a boost next time. And the extra policies or dedications get picked or ignored and the game goes on. But, in a recent game I had a very contested border with Fungus Khan, and noticed, to my amusement, that his cities, which were large, were revolting fast and his border receded basically to his capital. No more complaints about the size of my.. uhhh.. cavalry now. Anyway I decided to learn about the mechanics of Loyalty and I believe it is quite a clever system, and powerful when you know what you are doing. On their first iteration the designers obviously thought it was a bit too static (and boring) on a civ's borders and quite easy to bring to stability. But with the introduction of Dark and Golden Age modifiers it is a completely different beast and sole the reason for the Mongolian collapse. For me, at least, loyalty seems to be the primary reason for caring about Ages. I'm interested in hearing people's views on the matter. I'll share a spreadsheet which calculates loyalty pressure exerted by nearby citizens. Play with it and see the effects of Ages... It's configured to replicate (in one part) the Kongo-England example http://civilization.wikia.com/wiki/Loyalty_(Civ6) here.