Haraxx was a city within the Pharis Imperium. Long ago, it was conquered by the warlord Ten-ap. When he died, dozens of warriors and servants were sacrificed and interred along with him. However, he was also interred with an artifact known as the Dead Throne. Its power transformed him into an undead lich, and granted him the power not only to raise his servants from the dead, but to transform the city's inhabitants into the undead as well. Unfortunately, the throne's power was limited, and Ten-ap was unable to move far from it without breaking the enchantment and crumbling to dust.
And so Ten-ap sat within Haraxx, the city of the dead, for countless decades, until the Brightstone Heroes arrived. They fought their way through the hordes of undead to an ancient temple of Nalindra. Within, they found the now-undead priesthood. Turned against their will, they held no love for Ten-ap and desired only to be released from his curse and to know eternal peace with their goddess. Aided by the priests, the Brighstone Heroes stormed the palace, slew Ten-ap, and destroyed the Dead Throne, reducing all the undead in the city to dust. When the heroes found Ten-ap's treasure vault, they magically sealed it up, only to teleport back months later with the means to transport everything contained within it.
Today, Haraxx is a sand-scoured ruin, filled with the dessicated remains of its former inhabitants and those foolish (or unlucky) enough to cross them.