The Rage Curse
The Ordullian Dynasty was a golden age of mankind. Humans spread out using magic to do a great many things, raising cities, binding huge and frightening beasts to their will, even parley with their old gods. This society became decadent, and all but eradicated the power and history of the dwarves, enslaving them. Ordullians also destroyed the threat of the Dark Ones, an evil race that threatened to cover the world with their filth.
Some cataclysm destroyed the entirety of the Ordullian empire over a thousand years ago. It’s unknown how this happened, and scholars and archaeologists are working tirelessly to find out. This started the Age of Darkness.