Born in 1629, O'Flaherty was the last de jure King of Iar Connaught, and the last recognized chief of the O'Flaherty clan. He is perhaps most often associated with his elaborate history of Ireland, Ogygia. Drawing from numerous ancient documents, Ogygia traces Irish history back to the ages of mythology and legend, before the time of Christ. The book credits Milesius as the progenitor of the Goidelic people, an assertion which has since been called into question. Nonetheless, Ogygia is considered a definitive history of Ireland. O'Flaherty died in 1718.