The flag of Connacht is a heraldic banner of the arms of Connacht, a dimidiated (divided in half from top to bottom) eagle and armed hand. The arms of are recorded as such on a map of Galway dated 1651, now in the Library of Trinity College, Dublin.
These arms closely resemble those of the Schottenkloster or Irish monastery founded in Regensburg, Bavaria in the 11th century. However, it is unclear how the arms of Schottenkloster located deep in the heart of the Holy Roman Empire came to be associated with the province of Connacht in Ireland. A possible, though unlikely, answer to the problem can be found in Vatican Ms 11000 which contains a necrology of prominent Irish ecclesiastics and political rulers whose obituaries were recorded locally, apparently on the basis of their being substantial benefactors of the Schottenkloster at Regensburg. In the section of the aforementioned necrology headed 'KINGS', the initial entry relates to Donnchadh and Domhnall MacCarthy, rulers of Desmond, to whom the arms of the Schottenkloster were apparently conceded, presumably as arms of affection. If it can be assumed that the arms of the Schottenkloster were similarly conceded to the other royal benefactors noted in the necrology, then an explanation of the origins of the arms of the province of Connacht begins to emerge because the final entry in the necrology refers to Ruaidhri O Conchobhair. Ruaidhri's connections were with Connacht where he was king, his declining years having been spent in the monastery of Cong which itself had links with certain monastic institutions in medieval imperial Germany.