The Vilebranch tribe split off from the Amani Empire after the Troll Wars and returned to their ancestral lands, in the area that is now called the Hinterlands. Like all other forest trolls, the Vilebranch allied themselves with the Horde during the Second War under the leadership of Zul'jin, a famous troll hero from the Amani tribe. When the Horde was soundly defeated, Zul'jin disappeared, and the forest trolls abandoned their orcish allies.
Furious at the orcs' failure to live up to Doomhammer's promise, the Vilebranch trolls returned home and eventually discovered that the Revantusk tribe had moved into the area. The Vilebranch decided that the small Revantusk tribe would be an easy source of victims for rituals. The Vile Priestess Hexx is said to sacrifice people to the faceless blood God, Hakkar.
In this assumption, the Vilebranch were mistaken. The Revantusks fought back with strength and cunning, and the Horde began sending reinforcements to aid the Revantusk tribe. Nonetheless, thanks to their unusually large numbers, the Vilebranch trolls remain confident to this day that they will defeat the Revantusks once and for all.