 Nearly three centuries before the events of the first novel, the Seven Kingdoms of Westeros were united under the Targaryen dynasty by Aegon I and his sister-wives Visenya and Rhaenys, establishing military supremacy through their control of dragons.The Targaryen dynasty ruled for three hundred years, although civil war and infighting among the Targaryens was frequent.Due to being held and bred in captivity, their dragons became ever smaller until they finally went extinct.