There are a number of different nations in Vana'diel. As a player, you can align yourself with one of the following:
In addition to the three nations above, there are three additional nations/nation-states which can be visited in Vana'diel.
The three main nations above can also be visited in the past by installing the Wings of the Goddess Expansion Pack.
Two other nations also appear in Vana'diel, although they cannot be explored as they have been destroyed in the present timeline.
The Marquisate of Tavnazia which was a nation that flourished on the coast south west of San d'Oria but was destroyed during the Great War, as well as the Kingdom of Ephramad which once stood in the Arrapago Islands but was destroyed when they were invaded by the Empire of Aht Urhgan.