Cináed Kenneth MacAlpin (d. 858), son of Alpín and king of the Scots and Picts, is assigned to the Cenél nGabráin lineage of Dál Riata, although the authenticity of his lineage has been questioned by some modern historians. It seems that Cináed (‘Kenneth’) attained the kingship of the Scots of Dál Riata c.840. The previous year Éoganán grandson of Fergus and king of the Picts, who at a time of confusion in the Dál Riata kingship also dominated the latter realm, was slain by the vikings.
As Cináed first came to prominence with the help of Hebridean Norse allies, and subsequently arranged a marriage alliance with Amlaíb Find (Olaf the White), king of the Dublin Norsemen, there may well be reason to suspect complicity on his part. In any event, as his later career would show, Cináed was certainly a political opportunist. If he was not in fact, as the genealogists claimed, a great-grandnephew of the aforementioned king Fergus, the kingly forebears of Cináed could have been very distant indeed. Nonetheless, he secured a marriage-alliance with Cenél nÉogain, a dynasty of the Uí Néill confederation; his daughter Máel-Muire (d. 913) was the wife of the king of Tara, Áed Findliath (qv), and mother of his son Niall Glúndub (qv), who later succeeded to the same dignity. In 847/8, Drust son of Ferat, the last independent king of the Picts, was slain at Forteviot in circumstances that savour of treachery. Cináed at this point assumed the kingship of the Picts, probably in the right of his mother. It seems reasonable that he benefited from destabilisation created by the viking raids to build a combined Dál Riata–Pictish kingdom of Alba.
Cináed's dual kingship lasted till his death at Forteviot (858). He was buried on Iona. His immediate successor was his brother Domnall, although the principal line of later kings descended from his son Causantín. Cináed was not the first Dál Riata ruler to unite the two kingships: three earlier dynasts, including Causantín (qv) son of Fergus, had managed to do likewise. The achievement of Cináed, however, was that he changed the law in favour of patrilinear succession. This facilitated the suppression of the Pictish kingdom and the establishment of a continuous line of Dál Riata rulers which brought the Gaelic language and culture to the fore and created the medieval monarchy of Scotland.