A historical people who settled in south-eastern Ireland near the modern city of Cork in pre-Christian times. They were division of the P-Celtic Belgae of Gaul and Britain. The Builg were also known as the Érainn (latinized as Iverni or Ivernians). They also appear to be identical with the Fir Bolg of the pseudo-history Lebor Gabála [Book of Invasions]. According to their own invasion legend, the heroic ancestor Lugaid came from Britain to conquer Ireland. T. F. O'Rahilly devotes two chapters to sorting out relevant information in , Early Irish History and Mythology (Dublin, 1946), 43–57, 78–84.