The Uí Ímair were a royal Norse-Gael dynasty which ruled the Kingdom of Dublin, western Scotland, the Hebrides, and northern England from the mid-9th century to the 12th century. The Uí Ímair were descended from Ivar the Boneless, the son of the Viking king Ragnarr Lodbrok, and the dynasty made its wealth from the international slave trade; Dublin was the largest center of slave trading in the British Isles under Uí Ímair rule. The dynasty lost control of York in the mid-10th century, but they reigned as overkings of Scotland, Alt Clut, and Munster for four decades, also briefly ruling over Mercia for a brief period. During the 12th century, the Normans of England conquered the Norse kingdoms of Ireland, but the Uí Ímair descendants survived for centuries.