The World is Gone.
They called it Wild Magic when it’s effects were first seen – creatures changed beyond recognition, terrain changing overnight. Scholars soon realized that the changes were tied to the huge storms that swept across the lands periodically. The storms grew in intensity and soon the changes came to villages and towns – and the people in them. Only those within stone were completely safe, and the ancient homes of the dwarves’ were soon filled with refugees. From there is was only a few short years before nothing was left of the world that had once been – nothing except the towering peaks and dark tunnels under the earth. Nothing but stone.
In this time of change and loss, many turned to their gods for answers and for aid. But the gods no longer responded to their believers or their priests. Others turned to scholars, but the world had changed, making much of their lore useless. Some speculated that a rift had opened to the elemental plane of Air. Others argued that the world was being reshaped after a war of the gods that left all but one dead or destroyed. More practical scholars studied the storms and sought to learn their patterns, with little luck.
Then came the Cult of the Unchanging, a sect of creatures that appeared almost overnight. Creatures, not human, no two alike but yet similar in appearance. Chitinous on the outside as an insect, naked save for a harness carrying their tools and supplies. The first of these was slain when seen, but others came and were heard. Each one promised a return to life above the stone, promised that they could protect others from the storms.
Few would have listened, but other events within the tunnels made the risk seem worthwhile. The denizens of the Underdark began a long war to reclaim the areas lost to them, especially those areas that produced food. The refugees were caught between this war and the risk of believing the Cultists. Many chose to take the risk. Today there are many small communities existing once again in the world, islands of stability in an ocean of change. Trade has returned between these communities as well, using creatures newly discovered. All of this depends upon the Unchanging, the cultists who use their power to resist the storms.