The 19th century Gaelic scholar John O'Donovan states in his Ordnance Survey letters for County Galway, and his book, The Genealogies, Tribes and Customs of the Hy-Fiachrach, that Dunguaire was built by the Ó hEidhin clan, chiefs of Coill Ua bhFiachrach, the district around Kinvara, and also of Uí Fiachrach Aidhne an area coextensive with the diocese of Kilmacduagh covering the part of County Galway between the Burren and Galway Bay to the west and Slieve Aughty to the east.