Other than the continental Barrier, there is no formation capable of connecting the Ghost Realm and the Cultivation World!
So this must be the weakest spot of the Barrier! Perhaps some cultivators or monster beasts from the Cultivation World accidentally discovered this place, got sucked in by the formation, and thus inadvertently ended up in the Ghost Realm. Unable to leave for some reason, and with the Ghost Realm lacking spiritual energy and food, they could only wait here helplessly for death!
This also explains the origin of those piles of skeletons!
Chapter 102