Y-DNA Haplogroup of Niall of the Nine Hostages: R1b, (and The Cruachan).
R1b At the time Christianity was brought to Ireland it is thought that Fiachra’s son, Amalgaid, was ruling.http://en.wikipedia.org/wiki/Amalgaid_mac_Fiachrae
The Four Masters record Amalgaid’s death as 449 A.D. Amalgaid was succeeded as king of Connacht by his nephew, Ailill Molt. Ailill was a son of Nath I who ruled Connacht at an earlier date. Queen Medb. She had been given the kingdom of Connacht by her High-King fatherEochaid Feidlech who had de-throned the previous king Tindi Mac Conra over an act of treachery — But, is best known for starting the Táin Bó Cúailnge (“The Cattle Raid of Cooley”) to steal Ulster’s prize stud bull. http://www.rootsweb.ancestry.com/~irlkik/ihm/ire500.htm
Ailill later became king of Ireland upon the death of Loegaire mac Neill in 462. Twenty years later he was slain in the battle of Ocha by a confederacy of the descendants of Niall, aided by the Lagin and the Daui nAraidi — NIALL OF THE NINE HOSTAGES R1b Y-DNA (http://en.wikipedia.org/wiki/Niall_No%C3%ADg%C3%ADallach) :
Connaught was named after Con of the Hundred Battles it is traditionally noted. According to the ancient scribes, Connacht was ruled during the first century BC, by a king whose name was Eochaidh Feidleach. Legend has it that it was he who built the great palace at Rathcroghan,
once the stronghold of Connacht kings One of his descendants, Fearadach, ruled from Rathcroghan in 75 A.D. Fearadach’s son, Fiacha, was killed at Magh Cru during the revolt of the Aitheach Tuatha4 or Attacotti.
As the story is told, the Aitheach Fiacha decided it was time to take revenge against their oppressive Milesian rulers. They secretly planned a death-feast and invited Fiacha, his chieftains and supporters. During the feast, the insurgents attacked and massacred all, including Fiacha. The Attacotti then assumed the kingship, but were later vanquished by the great warrior, Tuathal Teachtmhar, who established the kingdom of Meath for himself. He was succeeded by his son, Felim. Felim was the father of the celebrated Conn Cet-Chatach (Conn of the Hundred Battles) who reigned as high king in the early sagas of the Tara kings. Con through Eochaidh Mugmedon who was king of the province at the end of the fourth century. Eochaidh’s grandfather was Cormac Mac Airt who himself was grandson of Conn.
He is said to have three sons by his first wife — Brioin, Fiachra and Ailill. A fourth son by another wife was the warrior, Niall Noigiallach (Niall of the Nine Hostages). The sept stronghold was at Durna Shelca, near (Carnfree) in County Roscommon. Niall moved across the Shannon where he founded the dynasty of Uisnech in Westmeath. He later assumed the high kingship at Tara. In early historical times the offspring of Brioin, Fiachra and Ailill separated into three dynasties — Ui Briuin, ancestors to the Sil Murray (O Conors and MacDermots); Ui Fiachra, ancestors to the O Dowds and O Heynes; and Ui Aillela, whose descendants left no mark in history, except their name is perpetuated in the barony of Tir-Errill in County Sligo. O’Rahilly, p.401 The early annalists tell us that Firbolg people survived as distinct tribes well into early historical times. In Connacht, they were the Ui Maine, Conmhaicne, and others farming alongside Ui Fiachrach and Ui Briuin families of the ascendancy Gaodhails.
In Leinster, they were the Ui Failige, Ui Bairrche and Ui Enechglaiss to mention but a few. In Ulster and in Munster many tribes can be identified whose pedigrees can be traced to the Firbolgs. Among the pre-Milesian tribes of Connacht were the Gregraige, a Firbolg tribe, that inhabited much of the western part of present day County Sligo between Loch Gara and the Ox mountains. Other tribes sharing the same area were the Gailenga and the Luigne, tribes of the Tuatha de Danann Celts from which O’Hara and O’Gara are descended The Ciarrage tribes or “black people” populated much of northwestern County Roscommon and are believed to have been the early lords of Airtech, an area corresponding to the present-day barony of Frenchpark.
Their seat was believed to be at Baslic near Castlerea. In Connacht as elsewhere, the continuous flow of invaders over many centuries and the inevitable assimilation has made it difficult at distinguishing, with certainty, which tribe belonged to which people. As the Milesians came to dominate, many of the earlier colonists were reduced to subsidiary tribes. Others, however, were powerful enough to exercise a substantial degree of sovereignty within their well-established territories and they managed to coexist with the new rulers. In the seventh century the Ui Briuin Ai began separating into three branches — Ui Briuin Seola (O Flahertys), Ui Briuin Breffney (O Rourkes) and Ui Briuin Ai (O Conors, MacDermots and others).
This was not unusual in Gaelic Ireland because inheritance customs were such they allowed multiple male heirs to compete for the leadership upon the death of the king or chief. To minimize dynastic contention, seldom avoidable, some leaders imposed their kinsmen as rulers of smaller neighboring kingdoms or set them up as abbots of monastic communities. When they subdued neighboring tribes they extracted tribute and allegiance, but did not take their land by conquest.
At the end of the seventh century the kingship reverted to the Ui Briuin Ai under Muiredach Mullethan (from whom the dynastiic name Sil Murray is derived). Muiredach’s son, Indretach (707-723), began an aggressive campaign to consolidate Sil Murray sway over the other Connacht tribes. Two centuries later the Sil Murray succeeded in dominating Connacht. Many of the earlier ruling tribes lost power, others fragmented or disappeared as tribal units altogether and, still others were forced into subsidiary status as expansion moved across the province. There were some, the O Monaghans and O Kellys among them, that sank into obscurity, but emerged again at a later date.