As a young man, he participated in the compilation of the Annals of the Four Masters, working with Mícheál Ó Cléirigh, Cú Choigcríche Ó Cléirigh, Peregrine Ó Duibhgeannain and other assistants.
•
He participated in the compilation of the years up to 1333 with Ó Duibhgeannáin, the Ó Cléirigh's writing the rest of the book to 1616.