The clan or people of Éile claimed descent from Céin (Cian), a younger son of Ailill Aulom and brother of Éogan Mór, and thus had kinship with the Eóganachta. It has been suggested that the Éile were actually of Laigin origin, and that they may in fact have been the rulers of the Cashel area before the rise of the Eóganachta, as suggested by their role in Eóganachta origin tales, such as the Senchas Fagbála Caisil.
Éile was bounded to the north by the Kingdom of Mide, to the south by Cashel and to the east by the Kingdom of Ossory. It consisted of the baronies of Clonlisk, Ballybritt, Ikerrin and Eliogarty. By the 12th century, approximately one thousand years later, it was much reduced in size.
The area then known as Éile was divided into two principal regions or lordships, the northern of which, called Éile Uí Chearbhaill (Ely O'Carroll), was ruled the O'Carroll family. The southern lordship, called Éile Uí Fhogartaigh (Ely O'Fogarty), was ruled by the O'Fogarty family, who may have been of a separate lineage, possibly Dalcassian, from the O'Carrolls. Alternatively they were actually kindred but regional politics influenced later genealogists to associate them with different provincial dynasties at different periods. John O'Hart finds an Uí Néill descent from Fogartach mac Néill for the O'Fogartys.
Ely O'Carroll originally belonged to Munster, but is now located in County Offaly in the baronies of Clonlisk and Ballybritt. The boundary between Ely O'Carroll and the ancient Kingdom of Mide is co-terminous with the present boundary between the diocese of Killaloe and the diocese of Meath. That portion of County Offaly which belongs to the diocese of Killaloe was Ely O'Carroll and originally belonged to Munster.
Ely O'Fogarty included the baronies of Ikerrin and Eliogarty, now in County Tipperary, Munster. After the Norman invasion of Ireland, these baronies were added to the Earl of Ormond's county palatine. The native chieftains, O'Meagher and O'Fogarty, were left in possession of their lands, but were obliged to pay tribute to the Earl of Ormond.
The O'Carroll princes are survived to this day by the prominent Carroll family of Maryland in the United States. Charles Carroll of Carrollton was a signatory of the United States Declaration of Independence. His branch of the family have been seated at Doughoregan Manor for over two centuries.
- 571 - The battle of Tola, by Fiachna, son of Baedan, son of Cairell, against the people of Osraighe and Eile; and they were defeated. Tola is the name of a plain situated between Cluain Fearta Molua and Saighir.
- AI669 - Death of Forchellach, king of Éile.
- 707, The battle of Dola, in Magh Ele, where Leathlobhar, son of Eochaidh, Cu Allaidh, and Cu Dinaisc, were slain.
- AI744, Death of Ardgal, king of Éile.
- M757/T762, Fogartach, son of Eochaidh, lord of Eile died.
- M847, Tuathal, son of Ceallach, lord of Eile, died.
- 874 Donnchadh, son of Maelseachlainn, was mortally wounded by the Eili.
- 888, A battle was gained over the Eili by Maelguala and the men of Munster, at Caiseal, in which many noble youths were slain.
- 900 - A battle was gained by Ceallach, son of Cearbhall, and by the Osraighi, over the Eili and the Muscraighi, in which fell one hundred and ten persons, among whom was Techtegan, son of Uamnachan, lord of Eili, and many others of distinction.
- M903, Cnáimheini, mac Maenaigh, tighearna Ele, d'ég.
- M975 - Seachnasach mac h-Iruaidh tigherna Eile do mharbhadh.
- c.1000 - Cearball mac Dublaidhe Duind appears king of Éile in MacLiacc poem 'Siath righ Gaela, glantar hi!'
- AI1022 - Death of Gilla Pátraic son of Cerball, king of Éile.
- 1023 - Tadhg, mac Briain, mic Cindeittigh, do mharbhadh do Eilibh i fiull, iar na eráil dia bhrathair féin do Dhonnchadh, forrae.
- AI1028 - Death of Ua Dubchróin, king of Éile.
- LC1033 - Aimhergin Ua Cerbhaill, king of Eile, died.
- LC1033 - A victory was gained by the Eile, in which Braen Ua Clerigh, and Muiredhach, son of Mac Gillapatraic, et alii multi, were slain.
- U1033 - A rout was inflicted among the Éile in which Braen ua Cléirig and Muiredach grandson of Gilla Pátraic and many others fell.
- AI1033 - Braen Ua Cléirig, king of Éile, was killed.
- M1050 - Maelruanaidh, son of Cucoirne, lord of Eile, was killed by his own people.
- LC1050 - Maelruanaidh, grandson of Cucoirne, king of Eile, died.
- U1050 - Mael Ruanaid son of Cú Choirne, king of Éile, was killed (by his own people).
- LC1058 - Ribhardan, son of Cucoirne, king of Eile, fell.
- M1071 - The son of Righbhardan, son of Cucoirne, lord of Eile, was slain in a battle.
- M1072 - Ua Fogarta, lord of Eile, was killed by Ua Briain.
- AI1071 - Rígbardán's son, king of Éile, was slain.
- M1121 - Ríghbhardán, mac Con Choirne, tighearna Ele do écc.
- M1145 - Finn Ua Cearbhaill, Tanist of Eile, was killed.
- M1152 - Domhnall, son of Righbhardan, lord of Eile, was slain by the son of the Long-legged (An Chos Fhada) Ua Cearbhaill.
- AI1058.4 Tairdelbach Ua Briain brought the son of Mael na mBó, and the Laigin, Osraige, and foreigners with him to attack Brian's son, and they burned the greater part of In Machaire as far as Luimnech. And the Munstermen themselves burned Luunnech lest the other party should burn it, and they were engaged as they were turning out of it, and a few of the others and a good many of the Munstermen were slain, including Ua Lígda, erenagh of Imlech Ibuir, the son of Cú Choirne, king of Éile, and Ua Gébennaig, king of In Déis Bec.
- M1163 - The son of Finn Ua Cearbhaill, lord of North Eile, was slain by Domhnall, son of Toirdhealbhach.
- M1174, Ruaidri h-Úa Cerbaill [Rory O'Carroll], Lord of Ely, was slain in the middle of the island of Inish-cloghran.
- AI1174 - A hosting by the grey foreigners, and they came into Éile. Domnall Ua Briain and the Tuadmumu assembled [against them] at Durlas Ua Fócarta, and a battle was fought between them, in which the grey foreigners were defeated, seven hundred or somewhat more being slain.
- M1205 - The son of Guill-bhealach O'Carroll, Lord of Ely, was slain by the English.
- C1318 - A great victory was gained over the English in Ely, by O'Carroll; and Adam Mares and many other Englishmen were slain.
- C1399 - Tadc O Cerbaill, king of Ely, was captured by the Earl of Ormond this year.
- M1432 - A great war broke out between O'Carroll, Lord of Ely, and the Earl of Ormond; and the Earl marched at the head of a great army into Ely, ravaged the country, and demolished O'Carroll's two castles.
- M1443 - Maelruanaid O Cerbaill, king of Ely, died this year.
- Eliogarty, barony in North Tipperary
- Ikerrin, barony in North Tipperary
- Thurles, stronghold of the O'Fogartys
- Ricamil, an O'Carroll site
- Birr Castle
- Leap Castle
- Crónán of Roscrea
- Byrne, p. 133, 180-1
- Charles-Edwards, p. 546
- MacCotter, p. 212
- Tuadmumu, The Kingdom of Thomond by Dennis Walsh
- O'Hart, p. 454
- [Leabhar na gCeart, pp. 78, 79, note i.]
- Hoffman and Mason
- Francis John Byrne. Irish Kings and High-Kings. Four Courts Press. 2nd revised edition, 2001.
- Thomas Charles-Edwards. Early Christian Ireland. Cambridge. 2000.
- Ronald Hoffman and Sally D. Mason. Princes of Ireland, Planters of Maryland: A Carroll Saga, 1500–1782. Chapel Hill: University of North Carolina Press. 2000.
- Paul MacCotter. Medieval Ireland: Territorial, Political and Economic Divisions. Four Courts Press. 2008.
- Donnchadh Ó Corráin (ed.). Genealogies from Rawlinson B 502. University College, Cork: Corpus of Electronic Texts. 1997.
- John O'Hart. Irish Pedigrees. Dublin: James Duffy and Co. 5th edition, 1892.
- Ely Carroll Map.