Laignech was originally called Leabhar na Nuachongbála, after Noughaval in Co. Leix, and was compiled by Aed Mac Crimthainn, head of the monastery at Tír-dá-ghlas (Terryglass in Co. Tipperary). It was compiled around a.d. 1150. The Rawlinson Manuscript appears to have been compiled about the same time at Clonmacnoise.

Professor Kuno Meyer, in his introduction to Liadain and Curithir; A Love Story (1900) listed 400 sagas and tales in manuscript. He added the figure of a further 100 that had been brought to light since he had compiled his list and mentioned an estimated additional 50 to 100 tales that could lie in libraries still undiscovered. He believed, therefore, that there were some 500 to 600 tales, of which only 150 had been translated and annotated when he was writing. Eleanor Hull, in the introduction to her work The Cuchullin Saga in Irish Literature (1898), made a similar estimation. It is surprising that the bulk of these manuscripts still remain unedited and untranslated.

Old Irish was the standard literary language throughout the Gaelic-speaking world until the late medieval period. The spoken language of the Manx and Scots had begun to diverge from the standard about the sixth or seventh century. There is evidence that shows that bards and storytellers wandered freely from one country to another plying their craft. We have an account of the chief bard of Ireland, Seanchán Torpéist (ca. a.d. 570–647), arriving on the Isle of Man with 50 of his followers and entering into a literary contest there. So the legends and tales of Ireland were a common heritage in Scotland and Man.

It was not until the sixteenth century in Scotland that a distinctive Scottish Gaelic literature (as opposed to the Common Gaelic of Old Irish) began to emerge. At this time the Reformation had caused the learned intercourse between Ireland and Scotland to diminish and, left to its own resources, a Scottish Gaelic tradition rose. The Book of the Dean of Lismore, a miscellany compiled in 1516 by the Dean of Lismore (Argyll), was a compilation of poems and sagas, including many about the Fianna of Fionn Mac Cumhail. Yet, curiously, though the book was written in Gaelic, it used an English phonetical form of orthography, the writers showing complete disregard for the Irish standard orthography. The main wealth of the mythological tradition among the Celts of Scotland lay in a continued oral tradition that was not copied down until the eighteenth and nineteenth centuries.