Bridei son of Beli (; died 693) was king of Fortriu and of the Picts from 672 until 693. Background Bridei may have been born as early as 616, but no later than the year 628. Bridei is described in a verse attributed to Adomnán as "son of the king of Dumbarton", indicating that he was the son of Beli, king of the British kingdom of Alt Clut; the grandson of Beli's predecessor Neithon son of Guipno; and the brother or half-brother of Beli's successor Eugein. The conflict between Bridei and Ecgfrith of Northumbria for Pictish supremacy is described in the poem Iniu feras Bruide cath ("Today Bridei Fights a Battle") as being over the legacy (forba) of Neithon, providing evidence that this Neithon son of Guipno, Bridei's grandfather, may have been the same person as the earlier Pictish king Nechtan grandson of Uerb, and that the Alt Clut dynasty into which Bridei was born may have had Pictish origins. Nennius' Historia Brittonum tells us that Bridei was King Ecgfrith's fratruelis (maternal first cousin), suggesting Bridei's mother was probably a daughter of King Edwin of Deira, and half-sister of the Northumbrian princess Eanflæd. The marriage of Bridei's parents would have marked an accommodation between Edwin and Neithon, extending Northumbrian influence into the lands of the Picts and of the Britons of the Clyde. Reign Accession Bridei's accession to the Pictish kingship seems at least in part to have been due to the influence of the Northumbrian kings Oswiu and Ecgfrith. Bridei was passed over several times for the succession to both the Pictish and Alt Clut kingships, probably as the fall of his grandfather Edwin of Northumbria in 633 diminished Bridei's political connectedness, but the marriage of his aunt Eanflæd to the newly-crowned King of Bernicia Oswiu in 642 would have seen him once again become well-connected to the centres of Northumbrian power. Bridei became king after the expulsion of his predecessor Drest son of Donuel from his kingdom, which was probably centred around the northern Pictish district of Fortriu, in 671. This event is normally assumed to be connected to the "Pictish rebellion" that culminated in the Battle of Two Rivers, suggesting Drest was probably leading an attempt to overthrow Northumbrian overlordship in the early years of Ecgfrith's reign, after the death of his powerful predecessor Oswiu. Expansion Bridei was one of the more expansionist and active of Fortrean