They prided themselves that over all their history, many foes had battered upon the Ulfort’s gates, but always to no avail - no uninvited guest had ever stepped foot within the hold. 
Ulrung took part in the Ghoul Wars and weathered the decade long Wailing Storm, standing against the Vampire alliance. Over the ages they expanded their underhalls, filling the Grand Vault with ur-gold. 
In the Time of Tribulations the Great Gungron, the immense furnace at the heart of the Temple of Fire went cold, depriving the holds defensive runes of power. Then the furnace began to burn with necromantic energy.