The Beastgrave was an immense predatory living mountain that lured explorers into its labyrinthine guts. While the name Beastgrave refers to a single mountain, the primitive tribes that live there often refer to the region around the mountain as the Beastgrave.
The cause of the mountain’s destruction is actually in dispute. Most believe it was destroyed as a consequence of Alarielle’s Rite of Life. However, others claim a band of Seraphon activated an arcane device that caused the mountain to tear itself apart from within. Still others insist that a deranged mob of Bonesplitterz consumed the mountain’s savage spirit and gleefully head-butted their way to freedom as the Beastgrave collapsed around them. The truth may never be known.