From the book:
Aruneus is a new world for use with the Pathfinder Role Playing Game. 100 years past, Aruneus experienced an apocalyptic event. Starting in a small village, a family infected by a strange sickness died, only to rise again several days later. Within weeks hordes of undead were roaming the Human empires, ravaging any warm blooded creature that fell in to their grasp. Aruneus was devastated - losing in a few years over 10 million sentient beings.
After 100 years of fending off a complete collapse, the sentient races are rebuilding their societies and for the first time there is hope that the undead menace can be destroyed and life given a chance to flourish again.
This supplement contains details on the Order of the White Cloth and magic users in the world of Aruneus, including the rise to power of the Order of the White Cloth and the fall of the Wizards under the Order’s rule.