THE CELTS: The Celts are an Indo-European people who, like the Germanic peoples, arose in situ. At their apex, Celtic peoples were found from the Iberian Peninsula east to Asia Minor; as mercenaries, they served in Egypt. They never constituted a single political entity, however, and eventually were absorbed or pushed to the edges of the British Isles. Today, native speakers of Celtic languages constitute the smallest of the Indo-European language groups.

CHRISTIANITY: The Celts had a great distrust of writing, preferring to trust to oral tradition. As a result, mythic texts are primarily the product of monkish redaction. The effect on the texts can be significant. Because the recording came late, the only evidence for continental myth comes from inscriptions and historical sources. Furthermore, the continental Celts had fused into a Romano-Celtic culture by the time evidence is recorded. Only in Ireland and Wales were the old traditions relatively untouched by Roman influence.

The monkish redactors Euhemerized the texts, but in the context of Celtic mythology the term has a specific meaning. Celtic Euhemerization refers to the reduction of mythic figures to a historical context. As a result, the texts can be difficult to recognize as myth on a first reading.

CELTIC AND GERMANIC: There are numerous similarities between Celtic and Germanic myth. On the continent the two cultures developed in geographic proximity to one another. Later, during the Viking Age, a considerable amount of Irish-Scandinavian interchange occurred. Sorting out which phase of contact was responsible for a given shared feature of myth is not always possible.