Dorwin developed into a sprawling and powerful empire early in the Third Era. Their mastery of technology, art, science, and magic was said to mirror that of the Elves, even though it has always been a Human-centric land. With a domain stretching far and wide, it seemed that there was nothing outside of its reach.
This came to an end in The Year of the Black Star, when a noxious fog known as the Blight started spreading at the heart of the empire, near its capital of Daith Emyr.
This fog persisted beyond weather, wind, and centuries, corrupting all life that found itself caught within. The initial appearance of the Blight had effectively decapitated the empire, with millennia of knowledge lost.
Those who survived were left searching for answers, and over time, the prominent school of thought posed that it must've been a punishment by something divine. The decadence of the old empire must have been the cause; punishment for a people getting too close to heaven. All history before the Blight was dubbed the Great Sin.
Between the factions and forces that survived the Blight, none were more powerful than the Holy Church of the One, which preached about the Great Sin and the necessity of reclaiming all that Dorwin had lost, except now in accordance to the will of the One True God.