The mythology of pre-Christian Ireland did not entirely survive the conversion to Christianity. However, much of it was preserved in medieval Irish literature, though it was shorn of its religious meanings. This literature represents the most extensive and best preserved of all the branches of Celtic mythology. Although many of the manuscripts have not survived and much more material was probably never committed to writing, there is enough remaining to enable the identification of distinct, if overlapping, cycles: the Mythological Cycle, the Ulster Cycle, the Fenian Cycle and the Historical Cycle. There are also a number of extant mythological texts that do not fit into any of the cycles. Additionally, there are a large number of recorded folk tales that, while not strictly mythological, feature personages from one or more of these four cycles

The sources

The three main manuscript sources for Irish mythology are the late 11th/early 12th century Lebor na hUidre which is in the library of the Royal Irish Academy, the early 12th century Book of Leinster in the Library of Trinity College, Dublin, and the Rawlinson manuscript B 502 (Rawl.), housed in the Bodleian Library at Oxford University. Despite the dates of these sources, most of the material they contain predates their composition. The earliest of the prose can be dated on linguistic grounds to the 8th century, and some of the verse may be as old as the 6th century.