Geoghegan

The sept of the MacGeoghegans is of the southern Uí Néill, and said to be descended from Niall of the Nine Hostages. Niall was alive from the mid 4th century into the early 5th century. His father was Eochaid Mugmedón, of the line of Erimhon, one of the sons of Esbain who it is said took Ireland from the Tuatha de Danann.

Niall's mother was Carthann Cas Dubh, daughter of the king of Britain. Niall's first wife was Inné, mother of his son Fiachu mac Néill, from who the Geoghegan family are said to be descended. He also had seven other sons with his second wife, Roighnech. Niall's ancestry is claimed by Irish myth to trace back to Miledh of Esbain, King of Spain, whose wife Scota was the daughter of the Egyptian Pharaoh Nectanebo II. From there the line is sometimes traced to Niul who was married to the daughter of Pharaoh Cingris.

Niall Noígíallach (Old Irish for "having nine hostages"),[1] or in English, Niall of the Nine Hostages, was a prehistoric Irish king, the ancestor of the Uí Néill dynasties that dominated the northern half of Ireland from the 6th to the 10th century. Irish annalistic and chronicle sources place his reign in the late 4th and early 5th centuries, although modern scholars, through critical study of the annals, date him about half a century later. He is presumed by some to have been a real person, or at the very least semi-historical but most of the information about him that has come down to us is regarded as legendary. There are various versions of how Niall gained his epithet Noígíallach. The saga "The Death of Niall of the Nine Hostages" says that he received five hostages from the five provinces of Ireland (Ulster, Connacht, Leinster, Munster and Meath), and one each from Scotland, the Saxons, the Britons and the Franks.[2] Keating says that he received five from the five provinces of Ireland, and four from Scotland.[3] O'Rahilly suggests that the nine hostages were from the kingdom of the Airgialla (literally "hostage-givers"), a satellite state founded by the Ui Néill's conquests in Ulster, noting that the early Irish legal text Lebor na gCeart ("The Book of Rights") says that the only duty of the Airgialla to the King of Ireland was to give him nine hostages.[4]^{: 222–232}

His son Fiachu mac Néill is said to be the ancestor of the Cenél Fiachach, a clan which included several well known sub-clans or septs such as Geoghegan and O'Higgins, whose lands extended from Birr to Uisnech in southern Westmeath and part of north Offaly and their southern territory became known as Fir Cell (land of the churches), and later the Barony of Moycashel.[5] His son Túathal established a northern branch and his son Úathnemgenn a southern branch. Another son Crimthann was great-grandfather of a local saint Áed mac Bricc (died 589).[6]

On the other hand, it is claimed in the early 15th-century manuscript called Leabhar Breac that the Geoghegans are descended, not from Fiachu, son of Niall, but from a plebeian, Fiachu, son of Aedh. This claim so enraged the descendants of Fiachu, that they killed the author of the passage, even though he was under the protection of Suanach, the abbot of the monastery of Rahin.[7]