Lebor na hUidre, or the Book of the Dun Cow, is the oldest Irish manuscript to contain primarily native narrative materials. It includes stories from the Ulster Cycle (including the oldest version of Táin Bó Cúailnge), Fenian Cycle, Mythological Cycle and Historical Cycle of Irish mythology, as well as religious and historical texts. It is held in the Royal Irish Academy. It is badly damaged: only 67 leaves remain, and many of the texts are incomplete.

It was created in the monastery of Clonmacnoise, County Offaly, and is the work of three scribes. Máel Muire mac Célechair (designated "M") and a second scribe (designated "A") wrote the original manuscript, working in tandem. Máel Muire is known from Irish annals to have died in a Viking raid on Clonmacnoise in 1106 CE, giving us a latest possible date for the main body of the manuscript. A third scribe, designated "H", added a number of new texts and passages, sometimes over erased portions of the original, sometimes on new leaves, probably in the later 12th or 13th Century, and presumably before 1359 when the manuscript was used to ransom several members of the O'Donnell family of Donegal who had been captured by Cathal Óg O'Connor of Sligo.

External links

• The text of the manuscript as edited by R I Best and O Bergin
• The contents of the manuscript, with translations of most of the texts
• Royal Irish Academy