I have long known that the world my debut series was set in would be the core world from which any other series tied into. What I did not know at the time, was that I would have to flesh in the world quickly.
Even before I finished the Followers of Torments saga, I had two other series starting to demand attention and a possible third, though at the time I wasn't sure if it would be a stand alone, or part of a third series as well.
And, so the World of Alterraden was born. Earth-like, primitive, and full of immense potential. Here is one of the first maps I worked up, along with a graph of just how the potential in this one world went from a single book, to a trilogy, to the Followers of Torments saga, and then exploded beyond even that.