Muiredach Bolgrach, son of Siomón Brecc, was, according to medieval Irish legend and historical tradition, a High King of Ireland. He took power after killing his predecessor, and his father's killer, Dui Finn, ruled for 13 months or four years depending on the source consulted, and was then killed by Dui's son ÃÂnna Derg. The Lebor Gabála ÃÂrenn synchronises his reign with that of Artaxerxes I of Persia (465âÂÂ424 BC). The chronology of Geoffrey Keating's Foras Feasa ar ÃÂirinn dates his reign to 674âÂÂ670 BC, that of the Annals of the Four Masters to 894âÂÂ893 BC. His son was FÃÂachu Tolgrach.