Lebor na hUidre

Lebor na hUidre or the Book of the Dun Cow (MS 23 E 25) is an Irish vellum manuscript dating to the 12th century. It is the oldest extant manuscript in Irish. It is held in the Royal Irish Academy and is badly damaged: only 67 leaves remain and many of the texts are incomplete. It is named after an anachronistic legend that it was made from the hide of a dun cow by Saint Ciarán of Clonmacnoise.