Around the turn of the 12th century there a number of important kings of Bréifne covered in the annals. Having lost the kingship of Connacht with the death of Aedh son of Art uallach Ó Ruairc in the year 1087, there was one last Ó Ruairc who attained notoriety as a king of Connacht: Domnall, a grand-nephew of the previous O'Ruairc king of Connacht Aedh Ó Ruairc. Domnall died in the year 1102. The Bréifne territory included the modern Ireland counties of Leitrim and Cavan and at one point in the 12th century, when Tighernán mór Ó Ruairc was king of Bréifne, it extended from Kells in County Meath to Drumcliff in County Sligo.

By about the 13th century the Bréifne region had split into East and West, the Ó Ruairc kings maintaining lordship over the West (an area in and around County Leitrim). Tiernan O'Rourk, an active military chief, governed here in the latter part of the 12th century, when the princes of Connaught and Leinster combined to expel him from his territory; and Dermod Mac Murrough, the king of Leinster, taking advantage of their success, carried off his wife Dervorghal; but the expelled chieftain having applied for aid to Turlogh, supreme king of Ireland, the latter not only reinstated him in his principality, but regained him his wife. The English, soon after their arrival, in conjunction with their ally Dermod, invaded the territory of Breffny, where, however, Dermod was twice defeated, and compelled to secure his safety by a precipitate retreat. O'Rourk afterwards made an unsuccessful attack on Dublin, when in the possession of Strongbow's forces; yet subsequently he joined Hen. II. against Roderic, king of Connaught.

The O'Rourks ruled over several subordinate septs, the principal families of whom were the O'Murrey's, Mac Loghlins, Mac Glanchies, and Mac Grannels, some of whose posterity still exist; the descendants of the last-named family are now called Reynolds, a corruption of the original name. The county is partly in the diocese of Ardagh, but chiefly in that of Kilmore. For purposes of civil jurisdiction it is divided into the baronies of Carrigallen, Dromahaire, Leitrim, Mohill, and Rossclogher.

North Connaught is connected with some of the earliest events in Irish history. According to our ancient annalists, it was in the time of Partholan or Bartholinus, who planted the first colony in Ireland, that the lakes called Lough Conn and Lough Mask in Mayo, and Lough Gara in Sligo, on the borders of Roscommon, suddenly burst forth; and in South Connaught, according to O'Flaherty, the lakes called Lough Cime (now Lough Hackett); Lough Riadh or Loughrea, and some other lakes in the county Galway, and also the river Suck between Roscommon and Galway, first began to flow in the time of Heremon, Monarch of Ireland, and Lough Key in Moylurg, near Boyle in the county Roscommon, first sprang out in the reign of the Monarch Tiernmas. On the arrival of the colony of the Firvolgians in Ireland, a division of them landed on the north-western coast of Connaught, in one of the bays, now called Blacksod or the Broadhaven. These Firvolgians were named Fir-Domhnan or Damnonians: and the country where they landed was called Iarras, or Iarras Domhnan, (from "iar," the west, and "ros," a promontory or peninsula, signifying the western promontory or peninsula of the Damnonians): a term exactly corresponding with the topographical features of the country; and to the present day the name has been retained in that of the half barony of "Erris," in the county Mayo. Many of the Firvolgian race are still to be found in Connaught, but blended by blood and intermarriages with the Milesians. When the Tua-de-Danans, who conquered the Firvolgians, first invaded Ireland, they landed in Ulster, and proceeded thence to Slieve-an-Iarain (or the Iron Mountain), in Brefney, and thenceforward into the territory of Connaught. The Tua-de-Danans were originally Scythians, who had settled some time in Greece, and afterwards migrated to Scandinavia or the countries now forming Norway, Sweden, and Denmark.

In ancient writings Ireland is called Fail, as in Inis Fail, signifying Insula Fatalis or the Island of Destiny: a name given to Ireland by the Tua-de-Dacans from a remarkable stone called the Lia Fail, signifying Lapis Fatalis, Saxum Fatale or Stone of Destiny. The Lia Fail is believed to be the stone on which Jacob rested: and sitting on which the ancient Irish Kings, the de-Danans and the Milesians were crowned at Tara. This stone was sent to Scotland in the sixth century by the Irish monarch Murcheartach Mor MacEarca for the coronation of his brother Fergus Mor MacEarca, the founder of the Scottish Monarchy. It had been used for many centuries at the coronation of the Scottish Kings and kept at the Abbey of Scone.

The territory of North Connaught is connected in a remarkable manner with the mission of St. Patrick to Ireland: Mullagh Farry (in Irish, Forrach-mhac-nAmhailgaidh), now "Mullafarry," near Killala, in the barony of Tyrawley, and county Mayo, is the place where St. Patrick converted to Christianity the king or prince of that territory (Enda Crom) and his seven sons; and baptized twelve thousand persons in the water of a well called Tobar Enadharc. And Croagh Patrick mountain also in Mayo, was long celebrated for the miracles it is said the saint performed there. A cone of quartize rising 2,510 feet over Clew Bay near the Atlantic Ocean, Croagh Patrick is the holy mountain of Ireland. Patrick climed the mountain and rang a bell causing the snakes to leap from the crest of the mountain. The bell is returned to Croagh Patrick each yeare where the pilgrims pass it three times at the last Sunday of July (Garlic Sunday).

The See of Killala was founded by St. Patrick. At Carn Amhalgaidh or "Carnawley," supposed to be the hill of Mullaghcarn (where King Awley was buried), the chiefs of the O'Dowds were inaugurated as princes of Hy-Fiachra; while, according to their accounts they were inaugurated on the hill of Ardnaree, near Ballina. This principality of Northern Hy-Fiachra comprised the present counties of Mayo and Sligo, and a portion of Galway; while the territory of Hy-Fiachra, in the county Galway was called the Southern Hy-Fiachra or Hy-Fiachra Aidhne: so named after Eogan Aidhne, son of Dathi, the last pagan Monarch of Ireland, who was killed by lightning at the foot ot the Alps, A.D. 429. This territory of Hy-Fiachra Aidhne was co-extensive with the present diocese ot Kilmacduagh; and was possessed by the descendants ot Eoghan Aidhne, the principal of whom were -- O'Heyne or Hynes, O'Clery, and O'Shaughnessy.

Cruaghan or Croaghan, near Eiphin in the county Roscommon, became the capital of Connaught and the residence of its ancient kings; and the estates of Connaught held conventions there to make laws and inaugurate their kings. At Croaghan was the burial place ot the pagan kings ot Connaught, called Reilig na Riogh or The Cemetery of the kings; here Dathi, the last pagan Monarch of Ireland, was buried; and a large red pillar-stone erected over his grave remains to this day. A poem, giving an account of the kings and queens buried at Cruaghan, was composed by Torna Eigeas or Torna, the learned, chief bard to the Monarch Niall of the Nine Hostages, in the fourth century, of the commencement of which the following is a translation:

"Under thee lies the fair king of the men of Fail,
Dathi, son of Fiachra, man of fame:
O! Cruacha (Cruaghan), thou hast this concealed
From the Galls and the Gaels."

The "Gaels" here mean the Irish themselves; and the "Galls" mean all foreigners, as the Danes, the Britons, etc. In the first line of the quotation Ireland is called Fail, as Inis Fail (signifying Insula Fatalis or the Island of Destiny): a name given to Ireland by the Tua-de-Danans, from a remarkable stone called the Lia Fail (signifying Lapis Fatalis, Saxum Fatale) or Stone of Destiny, which they brought with them into Ireland. This Lia Fail is believed to be the stone or pillar on which Jacob rested; and sitting on which the ancient kings, both of the De Danan and Milesian race in Ireland, were crowned at Tara.

This stone was sent to Scotland in the sixth century by the Monarch Murcheartach Mór Mac-Earca, for the coronation purpose of his brother Fergus Mor MacEarca, the founder of the Scottish Monarchy in Scotland; and was used for many centuries at the coronation of the Scottish kings, and kept at the Abbey of Scone. When King Edward the First invaded Scotland, he brought with him that Lia Fail to England, and placed it under the coronation chair in Westminster Abbey, where it still remains; though it has been erroneously stated in some modern publications, that the large pillar stone which stands on the mound or rath at Tara is the Stone of Destiny: an assertion at variance with the statements of O'Flaherty, the O'Connors, and all other learned antiquarians. Three of the De Danan queens, who gave their names to Ireland, namely, Eire (from which the name "Eirin" or "Erin" is derived), Fodhla, and Banba, together with their husbands, Mac Coill, Mac Cecht, and Mac Greine, the three Tua-de-Danan Kings slain at the time of the Milesian conquest of Ireland, were buried at Cruachan in Connaught. Among the Milesian kings and queens interred there, were Hugony the Great, Monarch of Ireland; his daughter, the princess Muirease; and his son, Cobthach Caolbhreagh; Bresnar Lothar; Maud (the famous queen of Connaught), Deirbhre, and Clothra -- all sisters of Bresnar Lothar, and daughters of Eochy Feidlioch; Conn of the Hundred Battles and the other sons of Felim Rachtmar) the 108th Monarch of Ireland; and other kings, descendants of Conn of the Hundred Battles, with tbe exception of his son Art, the 112th Monarch (who directed that he should be buried at Trevet in Meath), and of Art's son Cormac, the famous Monarch of Ireland in the 3rd century, who was buried at Ros-na-Riogh (now Rosnaree or Rosnari), near Slane in the county Meath.

The Conmhaicne Mara (the Conmhaicne of the sea) were Located in what is now the extreme west of County Galway and gave their name to the territory they occupied i.e. Connemara, which is the anglicised form of Conmhaicne Mara. Chiefs of Conmaicne Rein (Muintir Eolais) included Reynolds (Mac Raghnaill, Mac Rannall), with the O'Rourke (Uí Ruairc) dynasty cited as over-lords of this area. The site of Ballintaggart church and old burial ground on a hillock between Dingle Harbour and Trabeg. According to the "Book of Ballymote," this King Cormac, who had some knowledge of Christianity, gave orders that he, too, should not be buried at Brugh Boine (which was the cemetery of most of the pagan kings of Meath), but at Ros-na-Riogh; and that his face should be towards the rising sun! Brugh Boine (which signifies the "town or fortress of the Boyne") was a great cemetery of the pagan kings of Ireland, and, according to some antiquaries, was situated near Trim; but, according to others, more probably at the place now called Stackallen; between Navan and Slane in Meath.

In various parts of the ancient kingdom of Meath, in the counties of Meath, Westmeath, and Dublin, are many sepulchral mounds (usually called "moats"), of a circular form, and having the appearance of hillocks: these are the sepulchres of kings, queens, and warriors of the pagan times. There are several of these mounds of great size, particularly on the banks of the Boyne, between Drogheda and Slane; and one of them, at Newgrange, is of immense extent, covering an area of two acres; is about eighty feet in height; and was surrounded by a circle of huge stones standing upright, many of which, Ogham stones still remain. The interior of this mound is formed of a vast heap of stones of various sizes; and a passage, vaulted over with great flags, leads to the interior, where there is a large chamber or dome, and in it have been found sepulchral urns, and remains of human bones. Cairns or huge heaps of stones, many of which still remain on hills and mountains in various parts of Ireland, were also in pagan times erected as sepulchres over kings and chiefs.

The only Lakes calling for notice are those formed as already mentioned in the course of the River Lee. North of these lies another range running east and west, beginning on the west with the Derrynasaggart Mountains (2,133) on the buondary between Cork and Kerry midway between Macroom and Killarney.