From HorizonXI Wiki

There are a number of different nations in Vana'diel. As a player, you can align yourself with one of the following:

  1. The Kingdom of San d'Oria
  2. The Republic of Bastok
  3. The Federation of Windurst

In addition to the three nations above, there is one additional nation which can be visited in Vana'diel.

  1. The Grand Duchy of Jeuno

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.