ABSTRACT
Leinster, or Cóiced Laigen (the Fifth of the Laigin), is one of the ancient provinces of Ireland. The dominant inhabitants were the Laigin, who believed they came from Gaul in prehistoric times. There were links across the Irish Sea in the early centuries C.E., for the Lleyn peninsula in Wales takes its name from the Laigin. Traditions preserved in historical tales and the annals show that the Laigin controlled a vast territory before the sixth century, including much of Brega and Mide; this land was ultimately lost to the Uí Néill, but there were Laigin kings of Tara before the reign of Niall Noígiallach. By the seventh century, Leinster’s boundaries extended from the valley of the Liffey westwards to the Slieve Bloom Mountains, then southward around the highlands of Osraige and down the Barrow valley to the sea. It was divided into north Leinster, Laigin Tuathgabair, and south Leinster, Laigin Desgabair, and kings in each area enjoyed a considerable degree of independence. The main settlement was in the valleys of the Liffey, Barrow, and Slaney, and in the plains of Wexford and Kildare. In the latter area is the hillfort of Dún Ailinne (Knockaulin), a site comparable to Tara or Emain Macha, and an important centre of the early Leinster kingship.
