The Otherworld refers to the ancient Celtic abode of the Gods and the spoirits of the dead. The Otherworld was a place that existed concurrent with thew world of man, and existed underground, or over sea, usually to the far West. The Otherworld goes by many names, including Anwyn (Avalon), the Isle of apples to the Welsh, and Tir na Nog (Land of Youth) to the Irish. The Otherworld was not wholly inaccessible by the living; many mythological accounts and even folk tales tell of visits to the Otherworld, where time passes much more slowly- a few minutes there can be a lifetime in the human world.

The Tuatha De Danann

The Tuatha De Danann were the ancient Irish pantheon, and included some of the older, Gaulish Celtic deities. Tuatha De Danann is popularly assumed to mean "Children of [the Goddess] Danu," and refers to a mythical, semi-divine race who were perceived as some of the earliest inhabitants of Ireland, who colonized the land after defeating the slovenly Fir Bolgs and the fearsome, Fomorian giants. The De Danann were in turn defeated by the Milesians, ancestors of the modern Celts. After this defeat, the De Danann agreed to divide the land with the Milesians, with the Milesians taking the upper world, and the Tuatha De Danann taking the lower. The Tuatha De Danann were led by their chief, the Dagda, into the Otherworld through earthen passage-tombs.

The Sidhe-Mounds

When Iron-age Celts encountered the remnant of the previous stone-age culture, they assumed the curious monuments and underground tombs (called Sidhe) to belong to the ancient gods. These tombs were perceived to be entrances to the Otherworld. Eventually, the name for the earth-mound burial sites became the name for their supposed inhabitants as well. With the coming of Christianity, the Otherworld gods lessened in importance, and even gained a sinister cast. They became the fey (fata, after the Latin for fates), whose sighting usually meant death was immanent. Eventuially, they metamorphosed into the fairy-folk.

Related Resources:

• Druid/Celtic Religion
  Celtic and Druid faiths, beliefs, history, and culture, plus an overview of Druid groups and orders, events, and publications.
• The Druids
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• Hallowe'en History Hyteria
• Symbols of Druidry
• Druid Gallery