The revisionist theory is that The popular image of Brian—the ruler who managed to unify the regional leaders of Ireland so as to free the land from a 'Danish' (Viking) occupation—originates from the powerful influence of a 12th-century book, "Cogadh Gaedhil re Gallaibh" ("The War of the Irish with the Foreigners") in which Brian takes the leading role. This work is thought to have been commissioned by Brian's great-grandson Muirchertach Ua Briain as a means of justifying the Ua Briain claim to the High Kingship, a title upon which the Uí Neill had had a near-monopoly. Recent research has suggested that it might have been commissioned by Muirchertach's contemporary and cousin, Brian Glinne Maidhir, or at least someone favourable to the line descended from Brian's son, Donnchad.