After the death of Vrael in Duel at Utgard Mountain, Galbatorix had achieved his goal to defeat the Riders and now sought for a new purpose. When his lust for power called, he flew on Ilirea once more with the intention to assume undisputed control of the land.
Upon arriving, he went to the throne and slew King Angrenost upon it. He then took the crown from the dead King and anointed himself King of Alagaësia. With that, he effectively began the Empire, the core of which was the Broddring Kingdom.