Millenia ago, during the first war between deities for the multiverse, Bald Mountain was used as a gateway from which the Friends on the Other Side could come out and war with Zeus and the armies of good. The good guys won the fight and Zeus had Chernabog sealed away into the Other Side along with the armies of evil under this mountain. Ever since then, the Friends, also known as Devils for those who can discern their true nature, can only exit the Other Side via Bald Mountain. Even so, they cannot travel out during the day since they are weak to the purity of day itself or when church music is played. But that doesn't stop them from finding hidden portals in the Other Side that they can use to escape to the many worlds in the Disney multiverse undetected...
This mountain is based on an actual mountain in Slovenia, Mount Triglav.