Our sagas, myths and folktales had a long life in oral tradition before being written down. So conservative was that tradition that we can safely claim that in Irish we have the oldest vernacular literature in Western Europe.

The earliest Irish manuscript, the Würzberg Codex dates back to A.D. 700 although another, the Amra Choluim Chille is believed to be a genuine sixth century manuscript and the Senchas Mór has also been placed in the sixth century by most experts.

The great prose narrative literature, the literature of the imagination, is preserved in folio vellum manuscripts of which the oldest is Lebor na hUidre (The Book of the Dun Cow) written about the year 1100. Other important surviving manuscripts from that period include Lebor Laighneach (The Book of Leinster) written before 1160 and The Yellow Book of Lecan, a manuscript from the fourteenth century.

The imaginative sagas preserved in these manuscripts may, in fact, predate them by centuries since they were the creations of an already long established oral tradition. The sagas were traditionally narrated by the Fili an order of Druids, until the middle of the seventh century and only from then on transmitted and preserved by means of the written word.