From Labyrinthe Wiki
The Rorthril Fens of Bildteve, often referred to simple as The Fens, do not consider themselves for the Empire but that does not make them a separate kingdom. The rivers run through them, indeed they are evil because they soaked up much of the evil of the Empire that supernaturally flows to them along the rivers. They are a sponge, a filter. They were also, like the mountains and the Broken Lands and any place not cleanly dominated somewhat larger than they seem by the very dint of the fact that no one knows what is there so tales and troubles make them that much larger. They might be conquered but that will be an enormous effort. And despite what the whiter of heart might think, apart from a few raids they are not threat to the Empire – and indeed appear to serve some good as they leach evil away from elsewhere. So they are a threat, so they are a place where Mercenaries might tread – so what? It is a wild land and probably ever will be and here at least each know where the worst of it is.