Bridei son of Beli

Bridei established an expansionary policy however, and in a series of campaigns between 679 and 683 built a confederation of Pictish territories owing allegiance to him through alliance and conquest.

Bridei's victory at Dun Nechtain marked the end of Northumbrian overlordship over the Picts, the Gaels and many of the Britons; and saw him consolidate his extensive territorial control.

[4] The Picts largely occupied the lands in the east of modern Scotland north of the Forth and were originally a diverse group of peoples defined at least in part by never having been Romano-British.

[6] Most significant of these was Fortriu, which was located north of the Mounth around the Moray Firth, encompassing the areas around Forres and Inverness, and whose primary centre of royal power probably lay at Burghead, which was three times larger than any other enclosed site in Early Medieval Scotland.

[9] The southern Pictish lands south of the Mounth may have formed an Anglo-Pictish province controlled from Fife,[10] whose ruling family may have included the Northumbrian noble Beornhæth.

[11] A document written in Rome between 678 and 681 records the claim of the Northumbrian bishop Wilfrid to primacy over "all the northern part of Britain and of Ireland and the Isles which are inhabited by the races of Angles, Britons, Gaels and Picts".

[14] The marriage of Bridei's parents would have marked an accommodation between Edwin and Neithon,[14] extending Northumbrian influence into the lands of the Picts and of the Britons of the Clyde.

[17] Stephen also records that Drest had "gathered together innumerable nations (gentes) from every nook and corner in the north",[23] suggesting that the Pictish forces were not otherwise politically united.

[27] The Annals of Ulster record that in 676 many Picts were drowned in Loch Awe, also suggesting an aggressive regime under Bridei attacking northern Dál Riata.

[12] In the 680s Bridei seems to have turned his attention away from Argyll, with a campaign that started less than a year after the Northumbrian king Ecgfrith was weakened by his defeat by Æthelred of Mercia at the Battle of the Trent in 679.

[28] A series of conflicts recorded in Irish annals as taking place in northern Britain from 679 are likely to represent Bridei expanding his power base.

[30] The pattern of high-status sites attacked in Bridei's campaigns suggests they were the centres of independent provinces that resisted his rule, as he built a confederation of territories by alliance or conquest that owed allegiance and tribute to him as king.

[46] Bridei's reign saw the Dal Riatan kindred the Cenel Comgaill rise in prominence, gaining territory in the area of modern Clackmannanshire in the wake of Northumbrian withdrawal.

[14] Bridei's victory at the Battle of Dun Nechtain in 685, achieved by uniting various Pictish provinces under his leadership,[52] ended Northumbrian rule north of the Forth and extended the power of Fortriu southwards beyond the Mounth.

Approximate language zones in southern Scotland, 7th–8th centuries
Altclut on the River Clyde at Dumbarton , seat of Bridei's father Beli