From "Chapter VII: The Érainn"

The Érainn were the second of the Celtic groups to come to Ireland, as discussed in Chapter II. They arrived from the Continent between 500 and 100 B.C., and established their La Tène culture throughout the island as a military aristocracy possessing superior iron weapons technology. They were akin to the Belgae of Southwest Britain, and were generally known as the Ulaid in the North, and as the Erainn or Desi in the South, although all the tribes of this ethnic group were known ultimately to be Erainn. The great Erainnian population groups of around A.D. 600, such as the Muscraige of Munster, gave rise in the Middle Ages to the independently branched tribal groups that follow.
 

For a graphical representation of the major kinship groups, click here.

Key:

Major Kinship Group

Major Sub-Group

        Sept Name

            Branch Name

                    Sub-Branch Name

Clann Chointeagain

    Mac Giolla Phoil (MacGilfoyle)
 

Conmhaicne Rein

Muintear Eoluis

        Mac Raghnaill (MacRannall)

        O Cuirnin (O'Cornyn)
 

O Fearghaill (O'Farrell)

        O Maoileidigh (O'Moledy)
 

Muintear Giollagain

        O Cuinn (O'Quin)
 
 

Corca Dhuibhne

    O Failbhe (O'Falvey)

    O Séaghdha (O'Shea, Shee)

    O Conaill (O'Connell)
 
 

Corca Laoighdhe

    O Cobhthaigh (O'Coffey)

    O Duinnin (O'Dinneen)

    O hEidirsceoil (O'Driscoll)

    O Floinn (O'Flynn)

    O hAodha (O'Hea)

    O hAonghusa (O'Hennessy)

    O Laoghaire (O'Leary)
 
 

Corca Modhruadh (Corcomroe)

    O Conchobhair Chorca Modhruadh (O'Connor Corcomroe)

            Mac Cruitin (MacCurtin)

            O Lochlainn (O'Loghlen)

    O Dabhoireann (O'Davoren)
 

Corca Thine
 
        O Cathail (O'Cahill)
 
 

DaI Cairbre Arad

    O Dubhuidhir (O'Dwyer)
 
 

Dal gCais

Uí Toirdealbhaigh

        O Briain (O'Brien)

            Mac Consaidin (MacConsidine)

            Mac Domnaill (MacDonnell)

            Mac Giolla Iasachta (MacLysaght)

            Mac Mathghamhna (MacMahon)
 

        Uí Bloid

            O Eachtighearna (O'Aherne)

            O Cinnide (O'Kennedy)

                    O Cinneide Fionn

                    O Cinneide Donn

                    O Cinneide Ruadh

            O Seanacháin (O'Shanahan)

            O'Durack
 
 

Mag Raith (MacGrath)

O Fogartaigh (O'Fogarty)

O Gealbhain (O'Galvin)

O Grada (O'Grady)

O hAnradhain (O'Hanrahan)

O hlcidhe (O'Hickey)

O Meadhra (O'Meara, O'Mara)

O Maoldhomhnaigh (O'Molony)

O Murruanaidh (O'Moroney)
 
 

Cineal mBaoith

        O hArtagain (O'Hartagan)

        O Longargain (O'Lonergan)
 
 

Clann Dealbhaoith

        O Neill (O'Nihill or O'Neill of Thomond)

        Craobhach (Creagh)
 

Muintear Ifearnain

        O Cuinn (O'Quin)
 
 

Ui Caisin / Clann Chuileain

        Mac Conmara (MacNamara)

        Mac an Airchinnigh (Maclnerney)
 
 

Ui Fearmaic

        O Deaghaidh (O'Dea)
 
 

Cineal Guallachta

        O Griebhta (O'Griffey)

    O Faolain (O'Phelan, Whelan)
 
 

Partraige

    O Maille (O'Malley)
 
 

Uaithni

    O hlfearnain (O'Heffernan)
 
 

Ui Bairrche

    Mac Gormain (MacGorman)

    O Treasaigh (O'Tracy)
 
 

Ui Fidhgheinte

Ui Conaill Gabhra

        O Cuileain (O'Cullane)

        O Cinnfhaolaidh (O'Kinneally)
 
 

Ui Cairbre Aedhbha

        O Donnabhain (O'Donovan)

        Mac Inneirghe (MacEnery)
 
 

Ulaid

Dal bhFiatach

        Mac Duinnshleibhe (MacDonlevy)

        Mac an Ultaigh (MacNulty)

        Mac Con Ultaigh (MacNally)
 
 

Osraighe

        Uí Duach

        Mac Giolla Phadraig (MacGilpatrick, Fitzpatrick)

        O Braonáin (O'Brennan)
 
 

Dal Riada

        Cineal Loairn

            Clann Duibhne / Caimbeul (Campbell)

            Mac Giolla Bhratha (MacGillivray)

            Mac Aonghuis (Maclnnes)

            Cineal Baodan / Mac Giolla Eoin (MacLean)

            Mac Neachdainn (MacNaughten)

            Mac an Aba (MacNab)

            Clann Chatain (Clan Chattan)

                    Mac an Phearsoin (MacPherson)

                    Mac Dhaibhidh (Davidson)

                    MacBheathain (MacBean, MacBain, MacBeath)

                    Cattanach

                    Mac an Toisich (MacKintosh, by inheritance)

            Camshron (Cameron)

            Mac Giolla Onfhaidh (MacGillonie)

            Mac Mairtin (MacMartin)

            Mac Somhairle (MacSorley)
 
 

        Cineal nGabrain

            Mac Fhearghuis (Ferguson)

            Mac Fhearghuis (MacKersey)
 
 

        Siol Alpin

            Mac Grioghair (MacGregor)

            Mac Dhuibhshithe (MacFie, MacPhie)

            Mac Fhionghuin (MacKinnons)

            Mac Guadhre (MacQuarrie)