Rosguill, a promontory (or Ross) in the barony of Kilmacrenan, co. Donegal, between Sheep Haven and Mulroy bay, i.e. in the parish of Mevagh. O'Dugan (Poems) cites that Ros-Guill and Ros-Iorguil belong to MacGillatsamhais. Ros-Iorguil, or Irguill, is equated to Horn Head, to the west of Ros Guill, in the index to the Four Masters. Both areas are west of Fanad. Who the MacGillatsamhais' (Mac Giolla Shamhais) were is not known. The areas of Rosguill (now Downing's & Carrigart), Doe (now Creeslough & Dunfanaghy), Cloughaneely (now Falcarragh ) and Tory Island, were later ruled by the Mac Sweeneys from Doe Castle. These were the MacSweeney Na Doe (Mac Suibhne na d'Tuath), lords of Na Tuatha. The district called Na Trí Tuatha, or Tuatha Toraighe, was an area extending from Ros Guill and Mulroy Bay in the east to Gweedore Bay in the west, with Tory Island included. Note: Trí Tuatha, not to be confused with the Three Tuatha of county Roscommon.

The Cianacht encompassed the O’Connors (O Conchobhair) of Keenaght, and the Luighne, (Clan Cian) or race of Lugh including the families of O’Hara (O hEaghra) and O’Gara (O Gadhra). The O’Garas were once one clan with the O’Haras, and together their territory, Luighne, included the modern baronies of Corran and Leyney in South Sligo, and Gallen and North Costello (Sliabh Lugha) in Mayo. About the end of the tenth century the two families separated, and divided the territory between them, the O’Garas taking the Mayo portion.

The Dealbhna Eathra and Dealbhna Nuadat were closely related to the Cianacht and Saithne.

The Deal bhna Nuadat were centered on the other side of the Shannon, between it and the River Suck in County Roscommon, and were tributary to the Uí Maine. The Saithne were closely related to the Cianacht and Dealbhna. They originally inhabited a territory in the southern part of the kingdom of Brega, the kingship of which they in ancient times, including Dalriada, had shared with kindred groups.

The Ciarraighe Locha na nAirne were originally part of a greater kingdom, the tribal kingdom of Ciarraighe, centered at Cruachu (the ancient capital of Connacht). This kingdom was fragmented by the Uí Briuin of the North Gaels during the late eighth century or early ninth century. The Eile were originally a tribe of western King’s County (Offaly), where place-names recall their early residence in that region.

O'Dugan also mentions belong to O'Cearnachain (e.g. Kernaghan) and Muintir Dalachain over Tuath Bladhach (Bladhaigh). Tuath Bladhaigh, anglicized Tuath Doe, is a well known district situated between Sheep Head and Cloghaneely, placing it to the south of Ros-Iorguil. Cloghineely is noted by O'Donovan in connection with the Ua Baighill (O'Boyles) of Cloch Cinnfhaelaidh, where they held sway until perhaps the second half of the 14th century. Here they are cited as chiefs of na Trí Tuath before the MacSweeneys.

Finn Ros, aka The Rosses, in Tirconnell, the land of the O Forananes and O Carnahanes, according to O'Brien's Irish Dictionary. O'Dugan (Poems) places O'Furadhrain over Fionn Ros, and O'Donovan translates the surname as Farran or Forran. O'Donovan in his notes to O'Dugan's Poems cites Fionn-Ros, now the Rosses, was situated in the barony of Boylagh. The Rosses are marked on a modern map of Ireland in the civil parish of Templecrone, in the far north of the barony of Boylagh. The Rosses extends from Crolly Bridge in the north to Gweebarra Bridge in the south, embracing all the intervening coastline and islands, penetrating inland as far as the Derryveagh mountains and the alpinesque village of Doochary.

The territory of Trián Íochtair Baoighellach is described by O'Donovan (Four Masters) in "The Rosses", between Aranmore Island and the Gweedore river, in county Donegal. At least a portion of the Rosses region, if not all, was connected with the O'Boyles, near of a portion of the Tri Tuath area they once held.

Fánad, or Fanat, is the peninsula between Lough Swilly and Mulroy Bay, in the northeast of the barony of Kilmacrenan, county Donegal. The sept of Ua Bresleáin (O'Breslen or Breslin), a branch of the Cenél Enda (MacLysaght) although cited by others as a branch of Cenél Conaill, are noted as early chiefs of Fanad, later noted as Brehons for Maguire of Fermanagh. The Mac Suibhnes (Mac Sweeney Fanat) are not as chiefs of Fanad in the late 14th century.

The Cenél Enda (Énna or Eanna) Located in (Leitrim) the southern Co. Donegal and northern Fermanagh region. About the 5th century Enda, the youngest son of Niall of the Nine Hostages, received territory in modern co. Donegal.

The Book of Lecan places Cenél Enda mic Neill west of Lough Erne.

According to Ptolemy, LEITRIM, together with that comprised in the counties of Fermanagh and Cavan, was occupied by the Erdini, called in Irish Ernaigh, who possessed the entire county bordering on Lough Erne. Leitrim, together with that of Cavan and part of Fermanagh afterwards formed the territory of Breffny, or Brenny, which was divided into two principalities, of which the present county of Leitrim formed the western, under the name of Lower or West Breffny, and Hy Briuin Breffny, from Brian, son of Eachod, and grandson of Muredach, first king of Connaught of the Scottish race.

Sometimes this county was designated Breffny O'Ruark, O'Rorke, O'Roirk, or O'Rourk, from the name of the family that ruled over it from a very early period. Its subordinate divisions were Dromahaire, the present barony of the same name; Lietdrumnai or Liathdromen, the modern Leitrim; Munster Eolus, or Hy Colluing, the present baronies of Carrigallen and Mohill, the principal families of which were the Maghrannals, or Mac Granells,; and Hy Murragh, the modern barony of Rossclogher, of which the chiefs were the O'Murroghs or O'Murreys. For some time after the arrival of the English, the whole was considered to form the ill-defined county of Roscommon: but the O'Rourks maintained an independent authority in their territory until the middle of the 16th century.

The Book of Fenagh equates Cenél Enda extending from the river Errity to Barnesmore, barony of Tir Hugh, to Sruell in the barony of Banagh, in the county of Donegal. It is said the north-western limit was Farnagh in the parish of Aughnis, barony of Kilmacrenan. The eastern limit of his lands was the river Finn. Historians have also placed this early area on the borders of modern co. Donegal and Tyrone.

Located in northern County Leitrim, south of Dartry, in the present barony of Dromahaire (e.g. Ballinaglera parish). The sept of MacCogadhain or Mac Acadhain (Mac Cogan) were noted as early chiefs in this area. According to the Book of Fenagh, they were a branch of Conmaicni Réin comprising C. Cellachain, C. Maelsamhna, C. Taebhachain, C. Ubhan, C. Lughann, and C. Uanan. They claim descendancy from the first wife of Findellach, the son of Neidhe, and 5th in descent from Cumscrach. Clann Fermaighe - (Glenfarne)

An area known as Magh Ene was located at the southern tip of co. Donegal, perhaps alluding to the area described in the Book of Fenagh. The latter area was later dominated by septs of the Cenél Conaill (Conal Gulban, son of Niall of the Nine Hostages). There were numerous territories or tribe names known as Cenél Enda, Enna, nEnna, et al. Perhaps the more famous was the territory of Cenél Enda (or Tir Enna), just southwest of Inishowen, in nothern co. Donegal, ruled by septs whose genealogies are tied to the Cenél Eoghain; Northern Uí Neill (Eoghan, son of Niall of the Nine Hostages).

Teallach Eachdhach O'Dugan cites Mag Samhradhain (Magauran) over Teallach Eachdhach, now the barony of Tullyhaw in co. Cavan. Their genealogy is said to derive from Uí Briuin lineage, an early genealogy cited as: Tomas oc m. Fergail m. Tomais m. Briain bregaigh m. Donnchada mc. Gillananaem m. Gilla Isa mc. Gillananaem m. Muiredaig mc. Samradain (.i. Domnall) m. Conchobair mc. Fergaile m. Floind mc. Aengusa m. Conchobair mc. Taidcc m. Ruairc mc. Imair m. Coscraid mc. Dungail m. Oirechtaig mc. Eachach (a quo Teallach Eachach) m. Maenaigh mc. Baithin m. Brenaind m. Fergnaa m. Fergusa mc. Muiredaig mail m. Eogain Sreib mc. Duach galaig m. Briain.

Loctaed in northwest County Cavan, the name of an ancient tribe (Masraige) inhabiting the area about Magh Slecht, and attributed by some as Fir Bolg in origin. The sept of Mag Samhradhain (MacGovern or Magauran) were later cited as chiefs in the barony of Tullyhaw (Teallach Eachdhach). The Mac Tighearnáin sept (MacTiernan or MacKeirnan) are noted in the neighboring barony of Tullyhunco (Tellach Donnchadha) in the 13th century.

There was also a Cenél Enna centered in Moycashel barony, co. Westmeath, represented by the familes of Ua Braonain (e.g. Brennan) of Creeve, and Mag Ruairc (e.g. Groarke) of Teallach Conmasa. Cenél Enda septs are also cited for the Uí Fiachra Aidhne, the Uí Briuin, the Conmaicne and for the ancient Uí Ernáin of Leinster who migrated to Munster. Teallach Dunchadha O'Dugan cites Mac Tighernain (McTiernan, McKiernan) as chiefs of Teallach Dunchadha, now the barony of Tullyhunco in co. Cavan.

Their genealogy is said to derive from the line of the Uí Briuin, an early genealogy cited as: Gilla Isa m. Briain m. Matha m. Gilla Isa m. Sitriuca m. Duarccain m. Tigernain m. Imair m. Gillacrist m. Amlaib m. Tigernain m. Maenaig m. Gillananaem m. Ruaidri m. Aengusa m. Taidcc m. Gofraid m. Conchobair m. Gormgail m. Dunchada (o fuil Tellach Dunchada) m. Maenaig m. Baithin m. Brenaind m. Fergna m. Fergusa m. Muiredaig Mail m. Eogain sreib m. Duach T. m. Briain

O'Dugan cites MacTighernain (McTiernan, McKiernan) as chiefs of Teallach Dunchadha, now the barony of Tullyhunco in co. Cavan. Their genealogy is said to derive from the line of the Uí Briuin, an early genealogy cited as: Gilla Isa m. Briain m. Matha m. Gilla Isa m. Sitriuca m. Duarccain m. Tigernain m. Imair m. Gillacrist m. Amlaib m. Tigernain m. Maenaig m. Gillananaem m. Ruaidri m. Aengusa m. Taidcc m. Gofraid m. Conchobair m. Gormgail m. Dunchada (o fuil Tellach Dunchada) m. Maenaig m. Baithin m. Brenaind m. Fergna m. Fergusa m. Muiredaig Mail m. Eogain sreib m. Duach T. m. Briain