County Tipperary was the ancient home of Eile, Deisi Thuasgeart, Muscraige Tire, Dal Cairpri Araide (?), and Éoganacht Caissil. Territorial names in the 12th century included Ely and Hy Fogarta (Ormond), Muscraige Cuirc, Aradh Cliach, Hy Kerrin, Uaithni Tire and North Decies.

The inhabitants of this portion of the island are designated by Ptolemy the Coriondi. Aengus McNafrach, King of Munster in the fifth century, is said to have enlarged the territory of the powerful tribe of the Desii, occupying the present count of Waterford, by the addition of the southern part of Tipperary, then forming a district called Magh Femin, but afterwards designated Desie Thuasgeart or North Desie, to distinguish it from the more southern lands of the same sept. According to Vallancey, the chiefs of Magh Femin, whose principal residence was on the rock of Cashel, obtained the name Hy dun na mio, or "the chiefs of the hill of the plain," rendered by corruption O'Donnohue, and from them descended the Mac Carthies. The Desii maintained a separate sovereignty until overpowered by the first English invaders, against whom, however, they carried on a sanguinary and protracted struggle. The families then holding superior rank were those of O'Fogarty, occupying the territory about Thurles, anciently called Hy Fogarta; O'Brien possessing the tract bordering on the Shannon, below Lough Derg, called Aradh Cliach, and forming the present barony of Owney and Arra; and O'Kennedy, who held Muscraighe Thire, now the baronies of Upper and Lower Ormond. The names of several other smaller districts have also been preserved, such as Corca Eathrach, including the country around Holy Cross and Cashel, forming a considerable part of Goulin, or the Golden Vale; Eoganacht, a territory and sept to the north of this, around Thurles; and Hy Kerrin still further north. Ormond, the name of the northern part of the county, signifies East Munster.

Ancient tribes who were said to be conquered by the Éoganacht included the Érainn and the Mairtine. The Érainn was a name applied to a variety of tribal groups across Ireland, including the Ulaid in the north, and the Corco Loigde in Munster. The Mairtine have been described as a Firbolg (aka Érainn?) tribe round Emly in the southwest of modern co. Tipperary. Locations of Tuath Mairtine are described by various texts in Muscraige Mittine (about the barony of East Muskerry), Airther Feimhin (about Clonmel), Liacc Tuill, Tír Aedha Breoguin, and in Uí Cairpre (about the baronies of Carbery). The Éoganacht were a federation of tribes claiming a common lineage and spread throughout Munster. They were noted as kings of Munster from an early period until the rise of the Dal gCais in the 10th century.

Caissil, or Caisel, is an reference for Cashel, in County Tipperary. The Mac Carthaigh (Mac Carthy) family was a chief sept of the Éoganachta Caisil. Other septs of the Uí Aongusa an Deisceirt, descended from Aengus mac Nadfraich, included O'Callaghan, O'Sullivan, O'Keeffe, Mac Cárthaigh. The chief families spread into counties Cork and Kerry with the rise of the Dal gCais dynasty and the arrival of Normans.

Luachair (Lúachra) is the old name of a large district on the borders of Co Cork, Kerry and Limerick. Cairbre of Sliobh Luachra was on the Cork-Kerry border (Book of Munster). Éoganacht Locha Lein is described, by John O'Donovan, around the Lakes of Killarney, in and near the barony of Magunihy, in county Kerry. Early ruling septs of Éoganacht Locha Lein included Úa Cathail (O'Cahill), Úa Flainn, Úa Muircheartaigh (O'Moriarity), and Úa Cerbaill (O'Carroll). By the 12th century the Úa Donnchadha (O'Donoghues of Cenél Láegaire), driven north out of Cork, had conquered and settled Éoganacht Locha Lein. The O'Donoghues had also driven out the Ua Congaile (O'Connell) chiefs, who were also noted by various authorities as chiefs in the region of the barony of Magunihy. Uí Cairpri Luachra derives its name from an ancestor named Cairbre Luachra. The Annals of Inisfallen tell is that from Cairbre Luachra descend Aos Isti (tribe-name of the O'Moriartys?), Aos Alla (Duhallow, Co. Cork) and Aos Gréine (Pallasgreen, Co. Limerick).

Centered in or near the baronies of Kilnamanagh in co. Tipperary, and the neighboring barony of Coonagh in Co. Limerick. The Éoganacht Caille na Manach (aka Éoganacht Beag Chaisil) were centered in the barony of Kilnamanagh in west co. Tipperary. The Éoganacht of Durlas Airthir Cliach were said to be centered near Thurles, co. Tipperary, just east of the northern Kilnamanagh region. The Éoganacht Mhór Mumhan were cited in the barony of Middlethird, co. Tipperary, just east of he southern Kilnamanagh region. Another location is cited south of Kilnamanagh, in the barony of Clanwilliam, co. Tipperary. The Ó Dubhuidhir (Ó Duibhir or O'Dwyer) were noted as chiefs in in the barony of Kilnamanagh, County Tipperary. Keating (History) note the O Duibhidhir of Coill na Manach (Kilnamanagh) and Mag Cormain were the O'Brien's marshals of the hosts. In O'Clerys genealogies the O'Dwyers are listed under the lineage of the Osraighe.

Their near neighbors included: The O'Cuirc (O'Quirke) who ruled over a considerable territory in Clanwilliam prior to the Norman settlement, with their territory then known as Muscraighe Cuirc (aka Múscraige Breogain). O'Cuillen (O'Cullen) were cited as chiefs of Eoghanacht Aradh in the barony of Owney and Arad. Mac Uí Bhrian (Mac I Brien), a Dalcassian sept, were lords of Owney and Arra, their territory anciently referred to as Aradh Cliach and acquired from the O'Donegans around 1300. The sept claimed descent from the legendary Eoghan (Owen) Mór, father of King Olioll Olum of Munster. The sept was forced west from Tipperary to Cork before 1300, becoming prominent by this date and very powerful after 1400.

The name Allen in Ireland is derived from the native Gaelic O'hAillin Sept that was located in County Tipperary. The name was also brought to the country by settlers from England and Scotland in the seventeenth century. Hallinan, Hallion, Alleyn and MacCallion are among the recorded variants.