[1][2][7] At the onset of the historic period of Irish history in the 6th century, the territory of Ulaid was largely confined to east of the River Bann, as it is said to have lost land to the Airgíalla and the Northern Uí Néill.

[1] Ulaid ceased to exist after its conquest in the late 12th century by the Anglo-Norman knight John de Courcy, and was replaced with the Earldom of Ulster.

[7] The general scholarly consensus since the time of Eoin MacNeill has been that the Ulaid were kin to the Érainn,[23] or at least to their royal families, sometimes called the Clanna Dedad, and perhaps not their nebulous subject populations.

[34] Towards the end of the 5th century, the Ulaid sub-group Dál Riata, located in the Glens of Antrim, had started settling in modern-day Scotland, forming a cross-channel kingdom.

[35] It is to these boundaries that Ulaid entered the historic period in Ireland in the 6th century, though the Dál nAraidi still held territory west of the Bann in County Londonderry.

[7] By the mid-6th century, the Dál Riata possessions in Scotland came under serious threat from Bridei I, king of the Picts, resulting in them seeking the Northern Uí Néill's aid.

[36] In 563, according to the Annals of Ulster, an apparent internal struggle amongst the Cruthin resulted in Báetán mac Cinn making a deal with the Northern Uí Néill, promising them the territories of Ard Eólairgg (Magilligan peninsula) and the Lee, both west of the River Bann.

[7] In an attempt to have himself installed as High King of Ireland, Congal made alliances with Dál Riata and Strathclyde, which resulted in the disastrous Battle of Moira in 637, in modern-day County Down, which saw Congal slain by High King Domnall mac Áedo of the Northern Uí Néill and resulted in Dál Riata losing possession of its Scottish lands.

[3] The Dál Fiatach dynasty held sway over Ulaid until the battle of Leth Cam in 827, when they attempted to remove Airgíalla from Northern Uí Néill dominance.

[42] All but Ulfreksfjord were destroyed by the combined efforts of the Ulaid and the Northern Uí Néill, however as a result they deprived themselves of the economic advantages provided by prosperous Viking settlements.

[44] Sigtrygg didn't forget the Ulaid's refusal,[43] and in 1001 his fleet plundered Inis Cumhscraigh and Cill Cleithe in Dál Fiatach, taking many prisoners.

[49] In 1006, an army led by Flaithbertach marched into Leth Cathail and killed its king, followed by the slaying of the heir of Uí Echach Cobo at Loughbrickland.

[49] The battle of Craeb Telcha resulted in the inability of the Ulaid to provide any useful aid to Boru, when in 1006 he led an army made up of men from all over Ireland in an attempt to force the submission of the Northern Uí Néill.

[51][52] In 1022, Niall mac Eochaid, the king of Ulaid, inflicted a major defeat on Sigtrygg's Dublin fleet, decimating it and taking its crew captive.

The Ua Flainn were the ruling sept of the Airgíallan Uí Thuirtre as well as rulers of Fir Lí, both of which lay west of the River Bann.

In a process of gradual infiltration by marital and military alliances as well as growing pressure from the encroaching Cenél nEógain, they moved their power east of the Bann.

[64] In retaliation Mac Lochlainn led a force consisting of the Northern Uí Néill and Airgíalla into Ulaid killing many and expelling Eochaid from the kingship.

[66][67] A week later, Mac Duinn Sléibe returned with a great host from across Ulaid, and despite heavily outnumbering de Courcy's forces, were defeated.

[67] De Courcy would take advantage of this instability and over the following years, despite some setbacks, set about conquering the neighbouring districts in Ulaid shifting the focus of power.

[66][67] By 1181, Mac Duinn Sléibe and Cú Mide Ua Flainn, the king of Uí Thuirtre and Fir Lí in County Antrim, had come around and served loyally as sub-kings of de Courcy.

[71] Mac Duinn Sléibe, possibly inspired by the chance to restore Ulaid to its ancient extent, may have encouraged de Courcy to campaign westwards, which saw attacks on Armagh in 1189 and then Derry and the Inishowen peninsula in 1197.

Until the end of the 13th century, the Dál Fiatach, still led by the Mac Dúinnshléibe, retained a fraction of their power being given the title of rex Hibernicorum Ulidiae, meaning "king of the Irish of Ulaid".

[72] The Gaelic title of rí Ulad, meaning "king of Ulster", upon the extinction of Dál Fiatach was usurped by the encroaching Ó Néills of the Cenél nEógain.

[75][76] The chief churches, or more accurately monasteries, of the main sub-kingdoms of Ulaid were: Although Francis John Byrne describes the few La Tène artefacts discovered in Ireland as 'rather scanty',[86] most of the artefacts (mostly weapons and harness pieces) have been found in the north of Ireland, suggesting 'small bands of settlers (warriors and metalworkers) arrived' from Britain in the 3rd century BC, and may have been absorbed into the Ulaid population.

[96] According to medieval pseudo-historians a group of brothers known as the Three Collas in the 4th century founded the over-kingdom of Airgíalla after a decisive defeat of the Ulaid, and afterwards destroyed their ancient capital Emain Macha.

[7] The Ulaid feature in Irish legends and historical traditions of prehistoric times, most notably in the group of sagas known as the Ulster Cycle.

The chief hero is Conchobar's nephew Cú Chulainn, and the central story is the proto-epic Táin Bó Cúailnge, "The Cattle Raid of Cooley".

The historical Connachta were a group of dynasties who traced their descent to the legendary king Conn Cétchathach, whose reign is traditionally dated to the 2nd century.

[107] O'Rahilly and his followers believe the Collas are literary doublets of the sons of Niall Noígiallach, eponymous founder of the Uí Néill, who they propose were the true conquerors of Emain in the 5th century.

The Érainn, led by Cú Roí, also rule in distant Munster and, while presented as deadly rivals of the Ulaid, are again portrayed with unusual interest and sympathy.