During the revolution, taking the left bridge and then trying to take the bridge down there is an invisable wall. from what i saw that's the way forward but correct me if im wrong.
Not exactly. In the version you're playing now, the tuskers remain unpassable even after you beat him (I've fixed it for a newer version). So there is no static invisible wall, but if you beat the tuskers there (in a space you can't walk around them) in general, they will be invisible, but you won't be able to pass through them. It's a pretty major f@ck up on my part.