The Pins button, to the left of the minimap on the main campaign screen, enables player to set custom markers on the campaign map for any reason you wish. Player might earmark a particularly food-rich region for later conquering for example, or note the site of an epic victory (or defeat!). There are 18 different pin icons to choose from, and each may be tagged with a title and a short description.[1]
When starting a new campaign, the game will automatically mark several pins on the campaign map for the players to read relvent point of interests, objectives, and past storylines.