Errard McCoise
McCoise, Errard, chief poet of the court of Malachy Mor, King of Ireland, in the 11th century. O'Curry gives a particular account of his writings, and thus speaks of his Tale of the Plunder of the Castle of Maelmilscothach: "This tale is remarkable for the vigour and purity of the language in which it is told; but it is especially useful.. for the important corroboration which it contains of the authenticity of other ancient tracts and pieces, which go more or less into minute descriptions of the state of civilization and the social economy of the Gaedhil at the period spoken of; that is so far back at least as a thousand years ago."
Sources
261. O'Curry, Eugene: Ancient Irish Manners and Customs: Edited by W. K. Sullivan, Ph.D. 3 vols. London, 1873.