Ui Fiachrach Aidhne (the correct Irish spelling is Uí Fhiachrach Aidhne), a tuath (tribal kingdom) located in what is now the south of Co. Galway. In the centuries prior to the historical era, a branch of a dynasty called the Ui Fiachrach emerged as the ruling tuath in this part of Connacht. Their territory was known as Aidhne, Maigh Aidhne / Maigh nAidhne and also by the tribal name Uí Fhiachrach Aidhne. The diocese of Kilmacduagh is coextensive with the territory of Uí Fhiachrach Aidhne, which covers all of the barony of Kiltartan and large parts of the baronies of Loughrea and Dunkellin. In the eleventh century the Ó hEidhin / O Heyne / Hynes clan would emerge as the principal clan of the Uí Fhiachrach Aidhne. The Anglo-Norman invasion of Connacht in the 1200's considerably reduced the power of the Uí Fhiachrach Aidhne and the Clanricarde Burkes, the Norman family who led this invasion, captured a good deal of the north and east of the territory of Aidhne. After the 1200's the Ó hEidhin clan were largely confined to a sub district of Aidhne known as Coill Ua bhFiachrach, which is the area covered by the modern Catholic parish of Kinvara. The Ó hEidhin clan remained the lords of Aidhne up until they lost their power and lands after the Cromwellian conquest of Ireland in the middle of the seventeenth century.

Three other important clans of the Uí Fhiachrach Aidhne included the O Shaughnessys (Ó Seachnasaigh), the O Clearys (Ó Cléirigh) and the (Mac) Kilkellys (Mac Giolla Cheallaigh). The O Clearys were kings of the territory before the O Hynes clan but were exiled from the territory probably in the years following the Anglo-Norman invasion of Connacht. Under the patronage of the O Donnells of Ulster the O Clearys went on to become one of the most famous learned families in Ireland. Up until the late 1600's the O Shaughnessys held the sub district of Uí Fhiachrach Aidhne known as Cinéal nAedha na hEchtghe, which was also their clan name. Cinéal nAedha na hEchtghe consisted roughly of the civil parishes of Beagh, Kilmacduagh and Kiltartan and also parts of the civil parishes of Kibeacanty and Kilthomas. During the 1600's the O Shaughnessys became more important than the O Hynes clan even though the Ó hEidhin was still styled the lord of Uí Fhiachrach Aidhne. In the 1690's the O Shaughnessys had their lands confiscated for supporting the Jacobite cause against William of Orange. The senior line of the O Shaughnessys died out in the 1780's. The (Mac) Kilkellys held the sub district of Aidhne known as Cinéal Guaire, which is the area covered by the modern Catholic parish of Ballinderreen. They lost their lands in the Cromwellian confiscations during the middle of the 1600's.