Not much is known of the Tuatha de Danaan prior to their invasion of Ireland, other than that they came from four northern cities, Falias, Glorias, Murias and Finias, where they acquired their occult skills and attributes. On arriving in Ireland, some accounts state that they burned their boats behind them to prevent themselves from being tempted to return; the Book of Invasions states that they wafted in through the air as a host of spirits.
They then fought two battles, the Battle of Magh Tuiredh, on the west coast, in which they defeated the clumsy and ill-armed Tir Bolg, the indigenous population, and the Second Battle of Magh Tuiredh against the Formarians, after a guerrilla insurrection by the Formarians.
A third battle was fought against a subsequent wave of invaders, the Milesians, from Spain (who are thought to have been the Celts), who overcame the goddess, Eriu whom the Tuatha de Danaan sent against them. The Milesians were magnanimous in victory and named the island Erin, the dative form of her name, in her honour. Defeated, the Tuatha were led underground into the Sidhe mounds by The Dagda.