Quote Originally Posted by thegreatonemal View Post
Just like with any other new race being added they've always been here.
They've always been in the world, but not always in Eorzea specifically which is just the western continent plus surrounding islands.

Given both Viera and Hrothgar are from areas oppressed by the Garleans, I think it makes sense that adventurers of those two races started coming to Eorzea once they heard the Eorzean Alliance managed to free Ala Mhigo and Doma.