The fortress of Guldun was established about the same time as Harmugstahl, as a hidden redoubt in case of disaster. The survivors from the earthquake that destroyed Harmugstahl fled to Guldun. Dismayed at the loss of their main fortress and the secret weapon they had worked on for so long, they rebelled and forsake their allegiance to Tzeentch.
Disturbed by their lack of faith in The Great Plan, Tzeentch ceased his secret support for them and withdrew the magical energies he had provided.
Their sorcerous powers gone, the cultists were easy prey for the Imperial soldiers who came soon after. Their screams can still sometimes be heard, echoing through the bone-strewn halls of their hidden fortress.
In the southern part of the Broken Crags, near the trade route between the Downlands and the Uplands, various bandit groups and tribes have used the solid and well-hidden fortress as a base over the years, but each one seems to have been doomed from the start, soon running afoul of some disaster or greater force. There is currently a small band of Orc refugees inhabiting the ruins. Without a strong Warboss to lead them they sit in their holes all day scratching and eating, subsisting on the spoils from any caravan foolish enough to stray too close to the forgotten ruins of Guldun.