During the four hundred years of Roman occupation, the Celts in England became somewhat Romanized, but the Irish, and their near relatives the Scots, were less influenced by Latin civilization.

It is therefore in Ireland, Scotland, and Wales that the oldest traces of Celtic literature are found, for the bards there retained their authority and acted as judges after Christianity had been introduced, and as late as the sixth century.

Although St.
Patrick is reported to have forbidden these Irish bards to continue their pagan incantations, they continued to exert some authority, and it is said Irish priests adopted the tonsure which was their distinctive badge.

The bards, who could recite and compose poems and stories, accompanying themselves on a rudimentary harp, were considered of much higher rank than those who merely recited incantations.

They transmitted poems, incantations, and laws, orally only, and no proof exists that the pagan Irish, for instance, committed any works to writing previous to the introduction of Christianity in their midst.
The heroic tales of Ireland from a large and well-marked epic cycle, the central tale of the series being the anonymous "Cattle of Cooly," wherein is related the war waged by the Irish Queen Mab against her husband for the possession of a mystic brown bull.