From the post:
In the centuries since the First Darkness, the warriors of the Uthuk Y’llan have become nothing but a fearsome children’s tale to most of the inhabitants of Terrinoth. The great hordes of blood-crazed warriors and their demonic taint have faded into legend and obscure histories. Few details survive of the warriors of the Uthuk, whom many believed to be extinct.
The Uthuk are far from dead, however, and in the intervening centuries they have nursed their hatred of all others, even as the outside world has forgotten them. Amidst the savage wastes of the Ru Darklands, the tribes ready a new assault on their ancient foes: a swarm that could threaten all of Terrinoth.