Mount Thunderspire was once the western-most settlement of the Dawnforge Dwarves. They transformed the mountain into a village/temple devoted to the Dwarf God, Moradin.
Once humans moved into the region known as the Nentir Vale, they drove the Dwarves of Thunderspire out. They then sacked the temple and abandoned it to crumble into ruins.
The legend continues saying that a Red Dragon from the south made this mountain its home as it hunted the lands around Lake Nen. However, the dragon was believed to have moved on several years ago.