George R.R. Martin intended the original short story "In the lost lands" to be the first of a series of stories centered around Gray Alys which he intended to gather and release as a single volume, like his Tuf Voyaging. For various reasons he never came around to finish any more stories, but if the film adaptation turns out to be a hit he will write a new short story for a sequel to be based around.
The movie was stuck in Development for years at some point Keanu Reaves and Nicolas Cage were offered the role of Boyce.
The film has been in the works for several years. When Constantin Werner was attached to direct, Justin Chatwin was going to play Boyce.
It was filmed on two sound stages and several practical sets at Alwernia Planet near Kraków.