Lebor Gabála Érenn (Book of Invasions of Ireland)

The Book of Invasions form the major part of the Mythological Cycle. The Book of Invasions was supposed to contain the (fictional) history of Ireland. The cycle was written in the book titled Leabhar Gabhála or Lebor Gabala Erren - the "Book of Conquests" or the "Book of Invasions of Ireland". It was the stories of successive invasions and settlement of the Celtic people on Ireland. Five or six different people settled on the Isle.
The other main source come from Cath Maige Tuired (Second Battle of Mag Tuired (Moytura)), which was mainly centred on the Tuatha Dé Danann.
The main interests come from the race of Irish deities known as the Tuatha Dé Danann. They were supplanted by the Milesians, the last group of invaders, who became the ancestors of the modern Irish people.