The Mythical Cycle recounts the origins and history of the people of Ireland
begriming with the story of creation.
Lebor Gabala Erenn, known in English as The book of Invasions is a major part of the Mythical Cycle. It tells of the waves of invading tribes.
Another major work is Dinnshenchas, or Lore Concerning Places. This consists of poems which tell of the origin of Irish place names. I will be putting up some of these poems in the near future.
The stories in the Mythical Cycle, like so many, have been christianized in their translations, although it is possible to look beyond this and see the true stories.