Sigil

Human rednecks with bows and dire rat problems. There's horses and berries.

They were unknowingly protected from the forces of the undead by an evil artifact underground, which happened to also be summoning extra-planar creatures, a strange trade-off. Logically, the Legion of Boom destroyed it. Some people died, possibly. Who knows?

It was then super-destroyed when The Stale Lands plane shifted.