Brega, Ireland
Brega was an Irish petty kingdom which existed from the 425 to 1170 AD. It was founded by descendants of the O'Neill clan, and its kingdom included the Hill of Tara. During the 6th century, it was conquered by Ailech, and it split into two hostile branches during the 8th century. Brega was threatened by the Viking kingdom of Dyflin during the Viking invasions of Ireland and came under the suzerainty of Mide, and it was conquered by England during the Norman invasion of Ireland in 1170.
The name Brega translates as the “fair plain” a reference to the large, wide, fertile expanse of land that today straddles the modern counties of Louth, Meath and Dublin. To the east of Brega lay the Irish Sea and to the south, the River Liffey. The kingdom ran all the way north across the Boyne Valley and stretched as far as the mountains in Louth. The king of Brega at that time was Fínsnechta Fledach mac Dunchada.
County Meath & County Westmeath: Genealogy & Family History By Michael C. O'Laughlin