Lebor Gabála Érenn (literally "The Book of Ireland's Taking"; Modern Irish spelling: Leabhar Gabhála Éireann, known in English as The Book of Invasions) is a collection of poems and prose narratives in the Irish language intended to be a history of Ireland and the Irish from the creation of the world to the Middle Ages. There are a number of versions, the earliest of which was compiled by an anonymous writer in the 11th century. It synthesised narratives that had been developing over the foregoing centuries. The Lebor Gabála tells of Ireland being "taken" (settled) by six groups of people: the people of Cessair, the people of Partholón, the people of Nemed, the Fir Bolg, the Tuatha Dé Danann, and the Milesians. The first four groups are wiped out or forced to abandon the island; the fifth group represents Ireland's pagan gods, while the final group represents the Irish people (the Gaels).
The Lebor Gabála was highly influential and was largely "accepted as conventional history by poets and scholars down until the 19th century". Today, scholars regard the Lebor Gabála as primarily myth rather than history. It appears to be mostly based on medieval Christian pseudo-histories, but it also incorporates some of Ireland's native pagan mythology. Scholars believe that the goal of its writers was to provide a history for Ireland that could compare to that of Rome or Israel, and which was compatible with Christian teaching. The Lebor Gabála became one of the most popular and influential works of early Irish literature. Mark Williams says it was "written in order to bridge the chasm between Christian world-chronology and the prehistory of Ireland".