There is an impassable mountain in SE The Rift.I never saw a wall or circle. I went east and west but will not let me though the mountains in the rift to the south. Thx
You might have not noticed, but there is a fort to the east of that mountain. A road is leading through it. There is a pretty noticeable door inside of that fort.
You can only enter from one side of map. You will need to make your way around the map to other side of fort, either via an already-opened wayshrine or via exploration.