According to legend, the Rock first rose to political prominence in the fourth or fifth century AD, when a major fortress was established by the descendants of Eógan Mór who went on to establish a dynasty of kings-cum-bishops reigning over this part of Munster. The Eóganacht were ousted from Cashel in 978 by the Dál Cais line from Killaloe in County Clare, Brian Boru becoming the overlord of Cashel, and subsequently achieving dominance over Ireland in 1002. His descendant, Murtagh, granted the Rock to the Church in 1101 and, some fifty years later, when the papacy established four archbishoprics in Ireland, one of which was at Cashel, an early medieval cathedral was built here. By then, however, the Eóganacht had regained control under Cormac Mac Cárthaigh, who built the adjoining Cormac’s Chapel, finished in 1134. The whole site was sacked by Cromwell’s forces in 1647, but was still used by the Church of Ireland until 1749 when cathedral status was granted to St John’s Church on John Street.