An alternative theory was that by Eugene O'Curry, who suggested that Finn mac Gormáin transcribed or compiled the Book of Leinster for Áed.

[3] However, it is now commonly accepted that the manuscript was originally known as the Lebor na Nuachongbála, which is the "Book of Noghoval", now Oughaval (County Laois), near Stradbally.

This was established by R.I. Best, who observed that several short passages from the Book of Leinster are cited in an early 17th-century manuscript written by Sir James Ware (d. 1666), found today under the shelfmark London, British Library, Add.

These extracts are attributed to the "Book of Noghoval" and were written at a time when Ware stayed at Ballina (Ballyna, County Kildare), enjoying the hospitality of Rory O'Moore.

His family, the O'Moores (Ó Mhorda), had been lords of Noghoval since the early 15th century if not earlier, and it was probably with their help that he obtained access to the manuscript.

[5] Third, in the 14th century, the Book of Leinster was located at Stradbally (County Laois), the place of a monastery known originally as Nuachongbáil "of the new settlement" (Noughaval) and later as Oughaval.

The book, a wide-ranging compilation, is one of the most important sources of medieval Irish literature, genealogy and mythology, containing, among many others, texts such as Lebor Gabála Érenn (the Book of Invasions), the most complete version of Táin Bó Cuailnge (the Cattle Raid of Cooley), the Metrical Dindshenchas and an Irish translation/adaptation of the De excidio Troiae Historia, and before its separation from the main volume, the Martyrology of Tallaght.