How the gods of Ireland became the fairy people
When the Milesians — the ancestors of the Irish people — defeated the Tuatha Dé Danann in battle, the gods did not simply die or disappear. They made a deal. And the deal they made is why every hill in Ireland might have something extraordinary living underneath it.
The Division of Ireland
The Milesian poet Amergin divided Ireland between the two peoples: the Milesians would have the world above the ground — the farms and the rivers and the open sky. The Tuatha Dé Danann would have the world below — the fairy mounds, the hidden palaces beneath the hills, the underground realm that connected to the Otherworld beyond the sea.
The Dagda — the great father-god, who owned the fairy mound of Uisneach — assigned each of the Tuatha Dé Danann their own síde, their own mound. Oengus Mac Óg received Newgrange on the Boyne — which he had actually tricked his father out of earlier, in one of the tradition’s most charming legal manoeuvres. Lugh took his own mound. Bodb Derg became king of the Munster fairy mounds. Each god went underground — and the lights went on beneath the hills of Ireland.
What They Became
Underground, the Tuatha Dé Danann became something slightly different. They became the aos sí — the people of the fairy mounds — the beings that Irish tradition would call the fairies, though the word fairy barely captures what they were. They were not small. They were not sweet. They were the descendants of gods, living in an underground world that connected to the Otherworld beyond the western sea, occasionally breaking through into the mortal world at liminal moments — at Samhain especially, when the boundary between the worlds was thinnest.
Newgrange and Oengus
The most charming story in the Taking of the Fairy Mounds is Oengus and Newgrange. The Dagda had assigned the great mound at Newgrange to himself. Oengus came to him and asked for permission to spend a day and a night in the mound. The Dagda agreed. Then Oengus pointed out that “a day and a night” was the same as “all time” — since all time consists of days and nights. The mound was his. The god of love had outwitted the father of the gods with a single argument. Newgrange — one of the most extraordinary prehistoric monuments in the world, built to catch the light of the winter solstice — is still the home of Oengus Mac Óg in the Irish tradition.
The Fairy Mounds Today
The great passage tombs of the Boyne Valley — Newgrange, Knowth, and Dowth — the ring forts scattered across the Irish countryside, the low hills with their distinctive profiles against the Irish sky — all of these, in the traditional understanding, are the homes of the Tuatha Dé Danann. You don’t build on a fairy fort in Ireland. You don’t plough through one. The gods went underground, but they didn’t go away.
Key facts about The Taking of the Fairy Mounds
- Irish title: De Gabáil in t-Síde (“Of the Taking of the Fairy Mounds”)
- Context: Follows the Milesian defeat of the Tuatha Dé Danann — the gods go underground
- The Dagda’s role: Assigned each Tuatha Dé Danann figure their own fairy mound (síde)
- Newgrange: Oengus Mac Óg tricked the Dagda out of it with a legal argument about “a day and a night”
- The aos sí: What the Tuatha Dé Danann became underground — the fairy people of Irish tradition
- Samhain: The night when the boundary between the world above and below is thinnest
- Real sites: Newgrange, Knowth, Dowth — passage tombs on the Boyne; ring forts across Ireland
- Cycle: Mythological Cycle
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Link will appear as Taking of the Fairy Mounds: https://irishgodsandgoddesses.net - Irish Gods & Goddesses, March 22, 2026