Dál Riata was the kingdom of the Scotti an ancient Irish tribe, who spread from eastern Ulster in Ireland to Argyll and eventually gave their name to Scotland. Aidan mac Gabhrain, who reigned from 574 to 608 as king of Dál Riata, built a strong navy and waged aggressive war, raiding as far as the Isle of Man and the Orkney Islands. He was less successful in land battles and lost the Battle of Degsastan in 603 to the Angles. A census, the Senchus fer n'Alba of Dalriada exists.

The kingdom's power in Ulster was greatly diminished by a decisive defeat by the Ó Neill (Ui­ Neill) in 637 at the Battle of Mag Rath. From then on the Dalriadans focused on their lands in what is now Scotland. Their rivals were the Picts to the north and the Angles of Bernicia to the east. On the south they were bordered by Strathclyde, a Brythonic kingdom. The oldest written Goidelic language is Primitive Irish, which is attested in ogham inscriptions up to about the 4th century AD. The Cenél nAlbanaich, a Laigin tribe were a branch of the Oirghialla that settled in the northwest Highlands and Islands in very early times. Goidelic languages (Deer) were once restricted to Ireland, had identical sound shift (Q to P) independently in the predecessors of Gaulish and Brythonic such as Illyrian and Pictish. Sometime between the 3rd century and the 6th century a group of the Irish Celts known to the Romans as Scoti began migrating from Ireland. In contrast, the Romans referred to Scotland as Caledonia, a name derived from the Pictish tribe Caledonii. Following Coel Hen's death, his kingdom was continually divided among his descendants until, in the 6th century Urien became the king of a land called Rheged, which is assumed to approximately align with the current boundaries of Cumbria, but included annexes in Dumfries and Yorkshire.

The Déisi was a term used to describe a class of peoples in Tara of ancient Ireland that may lie at the origin of the mysterious people known as the Attacotti of Scotland and Ireland, who along with the Scots, Picts and Saxons, inspired so much terror in Roman Britain in the 360's under Magnus Maximus. The Déise were strongly maritime based in tradition and set up colonies in South Wales. It is the traditional county town of Brecknockshire, from Dyfed although its role as a county town diminished since the formation of Ely and Powys.

The Celts of Britain and Ireland had already converted to Christianity when the pagan Angles, Saxons, Jutes and Frisians invaded in the 5th century. Hiberno-Saxon Huns, Visigoths, Franks metalwork is believed to have been created at Dunadd including Gothic style from Scythians and the Sarmatians of the Greek Dark Ages.

Dál Riata (also Dalriada or Dalriata) was a Goidelic kingdom on the western seaboard of Scotland and the northern coasts of Ireland, situated in the traditional Scottish and Northern Irish counties of Argyll, Bute and County Antrim. The kingdom reached its height under Áedán mac Gabráin, but its expansion was checked at the Battle of Degsastan by Æthelfrith of Northumbria. The Senchus fer n-Alban lists three main kin groups in Dál Riata in Scotland, with a fourth being added later.

Although the monastery of Iona belonged to the Cenél Conaill of the Northern Uí Néill, and not to Dál Riata, it had close ties to the Cenél nGabráin, ties which may make the annals less than entirely impartial. The St. Martin's Cross on Iona is the best-preserved cross of its type, probably inspired by Northumbrian free-standing crosses, such as the Ruthwell Cross, although a similar cross exists in Ireland (Ahenny, County Tipperary). If Iona was the greatest religious centre in Dál Riata, it was far from unique. By the early 7th century there was a unified Pictish kingdom north of a line from the Clyde to the Forth rivers.

 

The Irish Kings of Dalriada
Book of Ballymote  Pedigree of the Scottish Kings 
Angus Turbech of Tara  Cenél
Fiachu Fer-mara  Cenél
Ailill Erand  Cenél
Feradach  Cenél
Forgo  Cenél
Maine  Cenél
Arnail  Cenél
Ro-Thrir  Cenél
Trir  Cenél
Ro-Sin  Cenél
Sin  Cenél
Dedad  Cenél
Iar  Cenél
Ailill  Eogan Cenél
Eogan  Eterscel Cenél
Eterscel  Conaire Mor Cenél
Conaire Mor  Admor Cenél
Daire Dornmor  Coirpre Cenél
Coirpre Crom-chend  Daire Dorn-mor Cenél
Mug-lama  Coirpre Crom-chend Cenél
Conaire Coem  Ellatig Cenél
Coirpre Riata  Lugaid Cenél
Cindtai  Mug-lama Cenél
Guaire  Conaire Cenél
Cince  Eochaid Riata Cenél
Fedlimid Lamdoit  Fiachra Cathmail Cenél
Fiachu Tathmael  Eochaid Antoit Cenél
Eochaid Antoit  Achircir Cenél
Aithir  Findfece Cenél
Laithluaithi  Cruitlinde Cenél
Sen-chormac  Sen-chormac Cenél
Fedlimid  Fedlimid Ruamnach Cenél
Angus Buaidnech  Angus Buidnech Cenél
Fedlimid Aislingthe  Fedlimid Aislingech Cenél
Angus  Angus Fir Cenél
Eochaid Muin-remor  Eochaid Muin-remor Cenél
Erc  Erc
Fergus  Fergus

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