The Eóganachta Tribe and Their Clans

The Eóghanachta Rule

The Eóghanachta Clan dominated southern Ireland from the 6th to 10th centuries from their seat in Cashel. In the 5th century this dynasty was founded by Conall Corc on and around the Rock of Cashel. 

The Eóganachta King Fíngen mac Áedo Duib ruled as King of Munster in the 7th century and is the direct male line ancestor of the O'Sullivans. His son Seachnasagh was too young to assume the throne and was therefore followed by Eóganachta King of Munster Faílbe Flann mac Áedo Duib, who is a direct male line ancestor of the later MacCarthy kings. This clan is remembered for their valiant defence of the Kerry region during the Viking Age.

During the Viking Age they were powerful in Munster and held territories often larger than their main rivals, the Uí Néill Clan, who had southern and northern groups. They never produced a High King or were at least not recognised as High Kings or Kings of Tara due to the unusual and complex system of Kingship in Ireland, which was itself largely dominated by the Uí Néills in the 9th century. Rather, they concentrated on their dominion as Kings of Munster in the territory south of an approximate line from Dublin to Galway.

The Fall of the Eóghanachta and Rise of Brian Boru

The Eóghanachta are remembered as generally peaceful and they treated their rivals and subjects fairly. Conquered kingdoms would be accorded status and freedom from tribute and as Munster was the wealthiest of the provinces this must be attributed to political skill rather than military might. They surrounded themselves with favoured subject clans that provided income as well as military defence. The Déisi Tuaisceart was such a clan and it is from this people that came the legendary figure of Brian Boru.

Brian Boru (Bryan Boru) was crowned King of Cashel and Munster in 977 and was the first non-Eóganacht king in over 500 years. His grandson Muircheartach Ua Brian passed the Rock of Cashel to the Bishop of Limerick and it was forever lost to the MacCarthys, the senior branch of the Eóganachta. St. Patrick, who came to Ireland before the Vikings, is said to have baptised Cashel’s third king, Aengus.

Other famous members of the Eóganachta include Feidlimid Mac Crimthain, and Cathal Mac Finguine. The former became King of Munster in 820 but is most remembered for the burning of many monasteries such as Clonmacnoise in the 830s. He took the abbacies of both Cork and Clonfert, and is recorded in the annals as full King of all Ireland in 840, but was unlikely to have been recognised as such. He was finally defeated by Niall Caille in 841, the northern king of their old enemies the Uí Néills.

By the 12th century, when the Kingdom of Munster split into the Kingdom of Thomond and the Kingdom of Desmond, the Eóganachta ruled the Kingdom of Desmond from the southern coast around Carbery until the 16th century.

Clans of the Eóganachta who fought and died beside Brian Boru, High King of Ireland at the Battle of Clontarf where O'Mahony, O'Donoghue, O'Donovan, Scanlan and O'Carroll among many others.

To Find Your Clan Search Below in our list of the Clans of the Eóganachta.........

Origin of the Long Clan Name

Origin of the Long Clan Name

The Irish Longs may have got their name from different origins, English, Scottish and Norman descent. A number of Irish Gaelic septs of O'Longain and O'Longaig contributed to the origin of this surname. One sept was located in County Armagh, but the greater numbers were in County Cork at Cannovee and also at Moviddy. This surname may also belong to that group of names which originate from a nickname attributed because of some characteristic. In this case it stems from the nickname origin, meaning being tall, lanky or long....read more

Origin of the MacGillycuddy Clan Name

Origin of the MacGillycuddy Clan Name

The MacGillycuddy clan were a sept of the O'Sullivans. The O'Sullivans were originally based in Tipperary but with the arrival of the Normans they were forced west to counties Cork and Kerry, where the name is common to this day. They were of the Eóganachta of Cashel, descended from Fingin Mac Aedh Duibh, king there from 601 to 618. The Gaelic origin is Mac Giolla Mochuda, which means son of the follower of Mochuda. O'Sullivan Mór sent his son to be educated by Saint Mochuda at Lismore. In Co. Kerry, the McGillycuddy Reeks still bear their name. They held a seat there in ancient times....read more

Origin of the McAuliffe Clan Name

Origin of the McAuliffe Clan Name

The McAuliffes where part of the MacCarthy sept, a powerful clan of the Eóganachta. The name is of Irish/Norse origin. It is derived from the Irish Mac Amhlaoibh meaning 'son of Amhlaoibh', or 'son of Amlaf' which was in turn derived from the Norse name Olaf. Though a Viking originator is not known of , it was common at the time (as it is today) to name children after St. Olaf who died in 1030, hence Olaf became Amhlaoibh, or Humphrey. It is known that the McAuliffes are descended from Amhlaoibh Álainn MacCarthy (Humphrey the Handsome), no doubt a colourful character from which a lineage began....read more

Origin of the McCarthy Clan Name

Origin of the McCarthy Clan Name

The name McCarthy is associated with the earliest of time and originates from Munster and the territory called Desmond. They were one of the most powerful dynasties in Ireland. After the central or MacCarthy Mór line, the MacCarthy Reagh, MacCarthy of Muskerry, and MacCarthy of Duhallow dynasties were the three most important dynasties of Mac Carthy. Oilioll Olum, the third century King of Munster, had two sons Eoghan and Cormac Cas. After his death North Munster was inherited by the Dalcassians, sons of Cormac Cas, and South Munster by the Eoghanachta, sons of Eoghan. ...read more

Origin of the O'Callaghan Clan Name

Origin of the O'Callaghan Clan Name

The name Callaghan originated from the name Ó Ceallacháin, and means descendant of Ceallachán. This is Gaelic for a word meaning 'strife'. The name comes from Ceallacháin Caisil, a king of Munster, who died in 954. It is said that he defeated Cinnéide, the father of Brian Boru in battle. They were displaced to the County of Cork, to an area near Mallow in around 1300. The first recorded spelling of the name in Ireland is dated back to 1605 in birth records in County Cork....read more

Origin of the O'Carroll Clan Name

Origin of the O'Carroll Clan Name

The name is derived from the Irish Ó Cearbhaill (descendant of Cearbhall). The name may originate from the Irish term Cearbh meaning “to carve” which may also in turn signify a butcher (another name for a fierce warrior!). The O' Carrolls trace their origins to the so-called Cianachta tribe, who were the Clan Cian or "Race of Cian" and dated from the 3rd century. However, this is disputed by some. The Cian in question was the youngest son of Olioll Ollum King of Munster....read more

Origin of the O'Connell Clan Name

Origin of the O'Connell Clan Name

The O’Connell name comes from the Eoganachta sept, Eoganacht Raithlind and originates as far back as 500 AD meaning it is one of the most famous and oldest family names in Irish History. The anglicized name for O’Connell is O Conaill, which means son of Conall. The name Connell comes from the possible meaning Cú (Con) meaning “Wolf or Hound”. They are descendants from the High King of Ireland, Aengue Tuirmeach in c 180 BC. ...read more

Origin of the O'Donoghue Clan Name

Origin of the O'Donoghue Clan Name

The Irish surname O'Donoghue comes from the gaelic name Ó Donachadha, meaning descendant of Donnchadh. This ancient Irish name means brown-haired man. They originated from Kerry where they held a family seat from ancient times. The O’Donoghues were a significant sept in County Kerry, in Desmond territory and had been driven there by the McCarthys.They also existed in Cashel, Galway and Cavan. Variations of the name are numerous and include Donoughue, Donough, Dunphy, Donohoe and many more. The first recorded settler of this name in the United States was Bridget Donaghue in 1850 in Boston....read more

Origin of the O'Donovan Clan Name

Origin of the O'Donovan Clan Name

The O’Donovan are descended from Donovan or Donnóbhán, which include the elements donn, dark brown and dubh, or black and the diminutive suffix án. The originator of this clan Donnuván mac Cathail was the 10th century ruler of the Uí Fidgentí kingdom based in West Limerick with the Rivers Maigue and Morning Star as boundaries. It is believed his mother was the daughter of the Viking King of Limerick, possibly Ivar, and his father Cathal the leader of the Uí Cairpre tribe. Its seat is said to have been Adare, Co. Limerick on the banks of the river Maigue. ...read more

Origin of the O'Driscoll Clan Name

Origin of the O'Driscoll Clan Name

The O’Driscoll name originates form the Irish name Ó hEidirsceoil, which means 'intermediary', 'diplomat' or 'interpreter'. Originally descended from the Corcú Loígde, one of the largest tribes of Celtic Ireland and based in West Cork, these rulers of Munster broke with the kingdom of Ossory and virtually disappeared from the political scene by the 9th century. at this time the Eóganachta were rising to power and many of the Corcú Loígde moved to join them or the influential Muscraige of Kerry....read more

Origin of the O'Keeffe Clan Name

Origin of the O'Keeffe Clan Name

The O’Keeffes are descendants of Caomh meaning”Kind, or gentle”. He lived in the eleventh century and was descended from Cathal mac Finguine, an 8th century King of Munster. They were active in the area of Fermoy, Co. Cork on the banks of the River Blackwater. With the arrival of the Normans many clans were pushed west and so the O'Keeffes settled in the barony of Duhallow, in Dromagh, Dromtarriff parish. O’Keeffes are found today mainly in counties Cork and Kerry....read more

Origin of the O'Kirby Clan Name

Origin of the O'Kirby Clan Name

The O’Kirbys were chieftains of the Eóganachta Áine (a princely house within the Eóganachta) between the 5th and 12th centuries. They were first found in Knockainey, Co. Limerick (Cnoc Áine or Hill of Áine). There was also a line of Kirbys that can be traced to County Mayo. During Norman times, from c 1200 on many clans were dispossessed and displaced to other territories. Their names became anglicised also. This name has several possible roots but it is thought that the Irish from comes from Ciarmhaic which means 'dark son'. The surname from this was O Ciarba....read more

Origin of the O'Leary Clan Name

Origin of the O'Leary Clan Name

The name O’Leary originates from the Gaelic name ÓLaoghaire or Ó Laoire, meaning descendant of Laoghaire (keeper of the calves). The O’Learys can trace their name from a 5th Century King, Lugaid Mac Con, an ancient High King of Ireland and King of Tara who was in turn a descendant of Dáire Doimthech. The O'Learys were part of the influential Corcú Loígde until the 9th century, when the Eóganachta rose in power and became the new overlords. They settled in the towns of Rosscarbery and Macroom in Cork....read more

Origin of the O'Mahony Clan Name

Origin of the O'Mahony Clan Name

The O'Mahonys came to the very south west of Ireland in the 6th and 7th centuries and belonged to the clans of the Eóganachta. They lost lands to the MacCarthys when they arrived here in the 12th century, and later to the O'Driscolls and the O'Donovans, but these clans were on good terms and conferred on French and Iberian fleets the right to fish and salt their catch at bases. Until the 15th century they were prosperous and building of religious houses and tower houses was common. Later their power declined due to British intervention and the events at Kinsale in 1602. Their leader at this time Donal O'Mahony escaped forfeiture due to his young age....read more

Origin of the O'Sullivan Clan Name

Origin of the O'Sullivan Clan Name

The name O'Sullivan is derived from the irish term meaning “one eye”, O Suilleabhain meaning one-eyed man. They originally inhabited the areas of Cahir in County Tipperary but today they are mainly found in Cork, Kerry and Limerick. When the Normans arrived in Ireland many clans were forced to retreat west as their homelands became parts of the new Norman or Anglo-Irish territories. Today it remains a very popular surname in Ireland and there are more than 200,000 carriers of the name Sullivan in the United States....read more

Origin of the Scanlan Clan Name

Origin of the Scanlan Clan Name

The name is originated from the ancient name Scannail which means “Of the Contentious One”. There were three separate septs: the O Scannail, from the counties of Cork, Limerick, Clare ad Kerry. Ballyscanlan in the County of Clare tooks its name from the Sept Scannell. they were a sept of the Eóganachta. The name Scannell has direct and allied links to Brian Boru and to the Battle of Clontarf in 1014. It is recorded that Eocha, son of Dundabach, Chief of Clan Scannail, and Scannail, son of Cathal, Lord of the Eóganacht Locha Léin, ...read more

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