According to David Sellar who was the Lord Lyon King of Arms in Scotland, the Book of Ballymote was written from between 1384 and 1405.

Other scribes of the book were Solomon O'Droma, a member of a famous County Fermanagh family, and a Robert McSheedy.

The book is a compilation of older works, mostly loose manuscripts and valuable documents handed down from antiquity that came into possession of McDonagh.

Patrick and his household; Cormac's instructions to a king; and a physical and geological survey of Ireland.

Part of the work is devoted to the sagas of Finn and Brian Boru, and the Lebor na Cert (Book of Rights).