They seem to have government types already available at the era. So I could see the "Republic, Oligarchy, Despotism" only available in the First Age, and then you have to choose from a new list of Governments in the Second Age, and another new list in the Third.The change of epoch, even if it would be better if it did not extend to the whole world, should also include a change of ideology, but the change of epoch and ideology comes from revolutions and ideologies: the Romance civil wars from Marius to Silla, to Caesar, and Pompey, and finally the Roman empire, the Russian revolution, France from monarchy to the directoire to Napoleon