of Irish fairy tradition is the fact that the fairy folk are far more definitely associated with special districts and localities and tribes and families than is the case in England.
We can detect a social organisation in many respects akin to that of mankind, we can draw up a map of fairy Ireland and say, here rules this chieftain, there that chieftainess has sway—nay more, these potentates of the invisible realm are named, we are informed as to their alliances and relationships, we note that their territory and interests seem at times to tally with those of the great septs which represent the tribal organisation of ancient Ireland. O'Brien is not more definitely connected with Munster, O'Connor with Connaught, than is this or that fairy clan.
If we turn from tradition as still recoverable from the lips of the Irish-speaking population of to-day, and investigate the extremely rich store of romantic narratives which, preserved in MSS. dating from 1100 A.D. to fifty years back, represent an evolution of romance extending over fully 1000 years (for the oldest MSS. carry us back some 200 to 300 years from the date of their transcription), we meet the same supernatural personages as figure in contemporary folklore, playing often the same part, endowed with traits and characteristics of a similar kind. Century by century we can trace them back, their attributes varying in detail, but the essence of their being persisting the same, until at last the very oldest texts present them under an aspect so obviously mythological that every unprejudiced and competent student of Irish tradition has recognised in them the dispossessed inmates of an Irish Pantheon. This mysterious race is known in Irish mythic literature as the Tuatha de Danann, the folk of the goddess Danu, and in some of the very oldest Irish tales, tales certainly 900 perhaps 1,100 years old, they are designated by the very term applied to them by the Irish peasant of to-day, aes sidhe, the folk of the sidhe or fairy hillocks.