The Iron Islands are one of the constituent regions of Westeros. The Iron Islands were long an independent nation confined to their islands before they invaded Westeros roughly a century before the War of Conquest, eventually going on to conquer the Riverlands. They were defeated by Aegon the Conqueror and forced to swear fealty to him. Aegon had to utterly destroy the then-ruling House Hoare during the Conquest, so allowed the ironborn to choose their new ruling house. They chose House Greyjoy of Pyke, who have ruled the islands ever since.