|Religion||Celtic polytheism, Celtic Christianity (coexistent)|
|-||fl. c. 340 AD||Eochu Liathán|
|-||13th century||independent princes|
|Historical era||fl. Late Antiquity|
The Uí Liatháin were an early kingdom of Munster in southern Ireland. They belonged the same kindred as the Uí Fidgenti, and the two are considered together in the earliest sources, for example The Expulsion of the Déisi (incidentally). The two have been given various origins among both the early or proto-Eóganachta and among the Érainn or Dáirine by different scholars working in a number of traditions, with no agreement ever reached or appearing reachable. It is entirely possible that they were the product of a combination of lineages from both these royal kindreds, or alternatively of another origin entirely.
Eochu Liathán ("Eochu the Grey"), son of Dáire Cerbba, is the eponymous ancestor of the Uí Liatháin.
The two most powerful septs of the Uí Liatháin were the Uí Meic Caille (including the Uí Anmchada) and the Uí Thassaig (later known as the Uí Meic Tire). Following the Norman invasion of Ireland, the Uí Meic Caille gave their name to the barony of Imokilly.
Career in Britain 
The Uí Liatháin are known from both Irish and British sources, respectively the Sanas Cormaic  and Historia Brittonum, to have had colonies in Wales and Cornwall. According to the Historia Brittonum they were driven out of North Wales by Cunedda and his sons.
Alongside the Uí Liatháin in this region of Britain were a significant force of the so-called Déisi, whose story is told in the famous Expulsion of the Déisi already mentioned above, as well as a smaller population of the Laigin. Neither are specifically connected to the Uí Liatháin, or connected to each other, in any of the Irish sources, but collaboration can certainly not be ruled out, especially in matters relating to trade, including the slave trade. The Déisi Muman lived adjacent to them in the neighboring County Waterford and the Laigin could be found not much farther east in the Kingdom of Leinster.
The Uí Liatháin can, however, be associated easily with their apparent relation Crimthann mac Fidaig, the legendary King of Munster and dominant High King of Ireland of the 4th century. They are mentioned not only in the same passage in the Sanas Cormaic, but are close relations in all the earliest genealogical manuscripts.
In a 1926 paper, Eoin MacNeill discusses the movements of the Uí Liatháin at considerable length, arguing their leadership in the South Irish conquests and founding of the later dynasty of Brycheiniog, figures in the Welsh genealogies matching Uí Liatháin dynasts in the Irish genealogies. He argues any possible settlement of the Déisi would have been subordinate until the ousting of the Uí Liatháin by the sons of Cunedda. The founder of Brycheiniog, Brychan, is in all probability the early dynast Macc Brocc (for whom see below), while the name Braccan also occurs early in the pedigrees of the Uí Fidgenti and Uí Dedaid, close kindred of the Uí Liatháin. MacNeill further associates this with the sovereignty in Ireland and conquests in Britain of their cousin germane, the monarch Crimthann mac Fidaig.
Bressal mac Ailello Thassaig was an early king of Munster according to one source. His sister Angias was the queen of Lóegaire mac Néill, High King of Ireland, and mother of Lugaid mac Lóegairi, who later became High King himself despite the initial wishes of Saint Patrick, thanks to Angias' beseeching the saint. She and Bressal were children of (Ailill) Tassach, son of Eochu Liathán.
At the Battle of Carn Conaill, the Uí Liatháin are listed among the Munster allies of Guaire Aidne mac Colmáin, a mention dismissed by Byrne, but discussed at length by Seán Ó Coileáin, who relates it to the cycle of Mór Muman and Ruithchern.
Later centuries 
A substantial part of the recently defunct kingdom was granted to the De Barry family by John of England in 1206, although the Uí Meic Tire persisted in a southern outpost for a few decades following.
Pedigree (illustrative) 
Dáire Cerbba / Maine Munchaín | |___________________________________________________________________________________________ | | | | | | | | | | Fidach Fiachu Fidgenid Eochu Liathán Uí Duach Argetrois Uí Dedaid | | |__________________________ |___________________________ | | | | | | Crimthann mac Fidaig Mongfind = Eochaid Mugmedón = Cairenn Ailill Tassach | | | | | | Connachta Niall Noígíallach | | _________| | | | Lóegaire mac Néill = Angias Bressal mac Ailello | | Lugaid mac Lóegairi
Septs and surnames 
The two most prominent septs of the Uí Liatháin were the following:
Uí Meic Caille 
The Uí Meic Caille (Uí Maic Caille), who gave their name to the Barony of Imokilly, took their name from Meic Caille, son of Meic Brócc, son of Eochu Liathán.
- Uí Anmchada ( Lane, Lyons, Lehane)
- Uí Glaissín (Glashan, Gleason, Gleeson)
- Uí Charráin (Ó Corráin, Curran)
Uí Thassaig 
These were the descendants of the aforementioned Ailill Tassach, son of Eochu Liatháin.
- Uí Meic Tire (Ó Mic Thíre, Mictyre, MacTyre, MacTire, Wolfe, Woulfe)
- ed. Meyer 1901
- Rawlinson genealogies, ed. Ó Corráin 1997, p. 195 (176)
- see Ó Corráin 1979
- ed. 1868, p. 111
- Byrne 2001, pp. 183-4
- ed. Morris 1980
- Morris 1980, pp. 20-1
- ed. Meyer 1901
- ed. 1868, p. 111
- Byrne 2001, pp. 183-4
- MacNeill 1926, pp. 128-32
- Byrne 2001, pp. 177-8
- Vita tripartita Sancti Patricii, ed. Stokes 1887, pp. 47, 557
- Stokes 1887, p. 465
- O'Nolan 1912
- The Cycles of the Kings by Dan M. Wiley
- Byrne 2001, p. 241
- Ó Coileáin 1974
- Ó Coileáin 1981
- ed. Ó Corráin 1997, p. 195 (176)
- ed. Stokes 1887, pp. 47, 557
- Byrne, Francis John, Irish Kings and High-Kings. Four Courts Press. 2nd revised edition, 2001.
- Chadwick, Nora K. (et al.), Studies in the Early British Church. Cambridge University Press. 1958. pgs. 122-3.
- Charles-Edwards, T.M., Early Christian Ireland. Cambridge. 2000.
- Cormac mac Cuilennáin, and John O'Donovan (tr.) with Whitley Stokes (ed.), Sanas Cormaic, or Cormac's Glossary. Irish Archaeological and Celtic Society. Calcutta: O.T. Cutter. 1868.
- Geoffrey Keating, with David Comyn and Patrick S. Dinneen (trans.), The History of Ireland by Geoffrey Keating. 4 Vols. London: David Nutt for the Irish Texts Society. 1902-14.
- Kelleher, John V., "The Rise of the Dál Cais", in Étienne Rynne (ed.), North Munster Studies: Essays in Commemoration of Monsignor Michael Moloney. Limerick: Thomond Archaeological Society. 1967. pp. 230–41.
- MacCotter, Paul, Medieval Ireland: Territorial, Political and Economic Divisions. Four Courts Press. 2008.
- MacNeill, Eoin, "Early Irish Population Groups: their nomenclature, classification and chronology", in Proceedings of the Royal Irish Academy (C) 29. 1911. pp. 59–114
- MacNeill, Eoin "The Native Place of St. Patrick", in Proceedings of the Royal Irish Academy. 1926. pp. 118–40
- Meyer, Kuno (ed. & tr.), "The Expulsion of the Dessi", in Y Cymmrodor 14. 1901. pgs. 101-35. (also available here)
- Meyer, Kuno (ed.), "The Laud Genealogies and Tribal Histories", in Zeitschrift für Celtische Philologie 8. Halle/Saale, Max Niemeyer. 1912. Pages 291-338.
- Morris, John (ed. and tr.), Nennius: British History and The Welsh Annals. Arthurian Period Sources Vol. 8. London: Phillimore. 1980.
- Ó Buachalla, Liam. "Contributions towards the political history of Munster" ii, in Journal of the Cork Historical and Archaeological Society 57 (1952): 67-86
- Ó Buachalla, Liam. "The Uí Liatháin and their septlands", in Journal of the Cork Historical and Archaeological Society 44 (1939): 28-36
- Ó Buachalla, Liam. "The Uí Meic Caille in pre-Norman times", in Journal of the Cork Historical and Archaeological Society 50 (1945): 24-7
- Ó Coileáin, Seán, "Some Problems of Story and History", in Ériu 32 (1981): 115-36.
- Ó Coileáin, Seán, "The Structure of a Literary Cycle", in Ériu 25 (1974): 88-125.
- Ó Corráin, Donnchadh (ed.), Genealogies from Rawlinson B 502. University College, Cork: Corpus of Electronic Texts. 1997.
- Ó Corráin, Donnchadh, "Onomata", in Ériu 30 (1979): 165-85.
- Ó Corráin, Donnchadh, "Prehistoric and Early Christian Ireland", in Foster, Roy (ed.), The Oxford Illustrated History of Ireland. Oxford University Press. 2001. pgs. 1-52.
- Ó Cróinín, Dáibhí (ed.), A New History of Ireland: Prehistoric and Early Ireland, Vol. 1. Oxford University Press. 2005.
- O'Donovan, John (ed. and tr.), Annala Rioghachta Eireann. Annals of the Kingdom of Ireland by the Four Masters, from the Earliest Period to the Year 1616. 7 vols. Royal Irish Academy. Dublin. 1848-51. 2nd edition, 1856.
- O'Nolan, Thomas Patrick (ed. & tr.), "Mór of Munster and the Tragic Fate of Cuanu son of Cailchin", in Proceedings of the Royal Irish Academy, Vol. XXX, Sec. C, No. 9. Dublin: Hodges, Figgis, & Co. 1912.
- O'Rahilly, Thomas F., Early Irish History and Mythology. Dublin Institute for Advanced Studies. 1946.
- Pender, Seamus, "The Uí Liatháin Genealogies from the Book of Ballymote", in Journal of the Cork Historical and Archaeological Society 43 (1938): 32-8.
- Sproule, David, "Origins of the Éoganachta", in Ériu 35 (1984): pp. 31–37.
- Sproule, David, "Politics and pure narrative in the stories about Corc of Cashel", in Ériu 36 (1985): pp. 11–28.
- Stokes, Whitley (ed. & tr.), The Tripartite Life of Patrick. London: Eyre and Spottiswoode for Her Majesty's Stationary Office. 1887.
- Mumu at www.rootsweb.ancestry.com