Era beginning/end
After the fall of Alfric the Cruel, a power vaccuum was created. To prevent another tyrant from rising, the former slaves put forward Ravgaal herself. However, she passed on the honor to a particularly diplomatic Goblin named Zildrivi. This Goblin would go down in history as Zildrivi the Kind. When word of both Gorax's death and Alfric's death reached the descendants of the slain Geowald the Brave in hiding, they found it safe to resurface. They presented themselves to Ravgaal, who was serving as Zildrivi's advisor at the time, and brought them to her. The Goblin instantly abdicated with the joking words 'Ah, the the people who I kept the seat warm for are here.', and then offered the Human royal family rightful throne back. This event served to forge an uneasy peace between the Humans, Orcs, Goblins and Dark Elves. This bond would grow over the centuries, and Humans grew accustomed to these races within their communities over time. While slavery had been abolished that day, only time and growing understanding could make the ensuing racism vanish.
This event was also a great blow to many an Overlord: with an ensuing shortage in troops, Heroes would continue to slay Overlords at an increased rate, leading to the eventual general downfall of the tyrants. In the present day, an Overlord is a rarity, and quick to be struck down in the early stages of their rise.