Edge of the Wild
From Tolkien Gateway
The Edge of the Wild was the counceptual boundary between most of Eriador, which was or had been a settled area, and the dangerous uplands leading to the Misty Mountains and the Wilderland beyond. Conceptually it was a north-south line that ran just to the west of the Ford of Bruinen.[2] When one was over, or east, of the Edge of the Wild even the best of plans could easily go astray, as Gandalf was well aware.[3]