The Scots in Dal Riada were dominated by the Picts.
The Picts faced a new Viking threat in the north of their land.
Alpin, Kenneth MacAlpin’s father, rebelled against the Picts.
Oengus II, High King of both Pictland and Dal Riada, split his army to fight the invading Vikings and rebellious Scots.
The Picts suffered disastrous losses and were defeated at the hands of Alpin. Oengus died that year.
Alpin marched north to attack the rest of the Pict army, and the Scots suffered a brutal defeat. Alpin was captured and beheaded.
The Picts suffered a devastating defeat at the hands of the Vikings who had by now conquered and settled in Shetland, the Outer Hebrides and as far south as the mouth of the Clyde.
From the west the Vikings attacked Dal Riada.
Brutalizing defeat killed most of Pictish nobility, including the High King of the Picts. Many Scots nobility were also killed.
Wrad became the High King of the Picts, ruling from the Supreme Kingdom of Fortriu.
Upon Wrad’s death in AD 842/843, the throne of Fortriu was contested by nine Pictish nobles. However it also opened up MacAlpin’s claim to the kingdom through his mother, who is believed to have been a Pictish princess.