The plain between the Boyne and the Liffey, coextensive with eastern Co. Meath, a portion of north Co. Dublin, and a small piece of Co. Louth. This includes the sites of Tara, Brug na Bóinne, and Knowth. The area took its name from Breaga, son of Breogan, but the dynasty of Brega claimed descent from Áed Sláine. Brega emerged as a political unit when the old kingdom of Mide dissolved in the 8th century, and it joined a reconstituted Mide at the end of the 11th. Tailtiu the Fir Bolg queen was thought to have cleared the forests of Brega. Conaire was given the taboo of not going right-hand-wise around Tara nor left-hand-wise around Brega. Many commentators prefer the latinized form, Bregia.