The Gurubashi and Amani empires had little love for one another, but rarely warred against each other. At the time, their greatest common enemy was a third empire - the civilization of Azi Aqir. The Aqir were intelligent insectoids who ruled the lands of the far west. These clever insectoids were greatly expansionistic and incredibly evil. The Aqir were obsessed with eradicating all non-insect life from the fields of Kalimdor.
The trolls fought them for many thousands of years, but never succeeded in winning a true victory over the Aqir. Eventually, due to the troll's persistence, the Aqiri kingdom split in half as its citizens fled to separate colonies in the far northern and souther regions of the continent.
Two Aqiri city-states emerged - Azjol-Nerub in the northern wastes, and Ahn'Qiraj in the southern desert. Though the trolls suspected that there were other Aqiri colonies beneath Kalimdor, their existence was never verified.
With the insectoids driven into exile, the twin troll empires returned to business as usual. Despite their great victory, neither civilization expanded much further than their original boundaries. However, ancient texts speak of a small faction of trolls that broke off from the Amani Empire and founded their own colony in the heart of the dark continent.