Province

Provinces are the land of the game to take over or to develop, provinces are basically much of the game's war or income/development systems that support those, otherwise those taxes would come from no where, and there would not be any manpower etc because it's all based upon systems implemented into the provinces. Countries depend on them in the game for development and survival but do not need massive amounts to be a rich or strong country, just that it can not compete with some others, which is fine. Development and Taxes can be explained elsewhere just look around on the Wiki!