The Barrowbrook Frontier
Though orcs are known to the inhabitants of the world, there are none. Nobody is really sure why; there are no living beings who remember the orcs, and there is no evidence of their presence to be found. Yet the memory of them lingers like a nightmare one has just woken from, and in tales of the bogey-men that parents tell their children to bring them in line.
Planar travelers who have been to other worlds know of (and have met) orcs, but orcs do not come to Parthenos.