The original ethno-tribal invaders known as the Gaels were the last of a series of Celtic invaders that would come to be considered native to the Emerald Isle after the beginning of the historical period (about A.D. 500—see Chapter III.) They arrived in Ireland sometime during the first century B.C., and brought a distinctive language, the ancestor of modern Gaelic, which would come to dominate the hybridized Gaelic culture that emerged from the prehistoric melting pot of Ireland (hence the later general appellation "Gaels" which was applied to all Gaelic-speaking people of Ireland—and later Scotland). Two great tribal nations of Gaels emerged in the light of the historical period: The North Gaels and the South Gaels or Eoghanach. Between about A.D. 1 and 400 the North Gaels expanded their foothold in the northwest of Ireland and established themselves as Sacral ("totemistically" sacred) High-Kings at the ancient site of Tara near Dublin with the aid of their allies, the Laiginian tribe of Oirghialla. These events are enshrined in the heroic tales of the Ulster Cycle of literature or Red Branch, one of the three great collections of early Irish literature along with the Finn Cycle and the later (medieval) Cycles of the Kings (as opposed to ordinary folk-tales). Because of the royal tribal preeminence of the North Gaels, clans representative of other ethno-tribal groups sometimes tried to affect genealogical connection to their sacred ancestral tribal stem as a kind of "social climbing," but only the unstudied were fooled by these generally half-hearted attempts. Similar circumstances prevailed in the South, among the long dominant Eoghanacht.

The North Gaels