The tribes to the north of Hadrian’s Wall were largely undisturbed by the Roman occupation of Britain. A Roman document of the 3rd century mentioned the Picti, a new tribal group that had established a dominant position in the country. Scholars suggest this was a Romanised version of a tribal name, or that they tattooed their bodies (picti is Latin for 'painted people'). They are thought to have been an indigenous people with a non-Indo-European language. They were later subdued by Celts - not from within Scotland, but from overseas. In the 5th century a Celtic tribe from Northern Ireland settled on the west coast of Scotland.
The invaders were called Scots. (Yes, the original Scots were a tribe from Northern Ireland). The Scots established the kingdom of Dalriada in both what is now Northern Ireland and the south west of Scotland. By the 9th century the Irish Dalriada succumbed to Viking raids, but in Scotland the Dalriadan kings established themselves and withstood constant Viking pressure from all sides.
Monasteries of the time owned sufficient wealth to attract Viking marauders. Lindisfarne on the east coast of Northumberland was raided in 793 and Iona, on the west coast of Alba, three times in a decade (in 795, 802 and 805). Even monasteries which seemed secure on inland rivers fell victim to longships rowing upstream. During the 9th century, the raiders settled in the Scottish islands and the Isle of Man and seized territory on the mainland of both Britain and Ireland. In 838 Norwegians captured Dublin and established a Norse kingdom in Ireland. From 865 the Danes settled in eastern England.
The MacAlpin line
A recognizable Scottish kingdom had appeared by the mid-9th century. Some suggest the year 843 to be the important date, but it was Kenneth MacAlpin, king of the Scots since 840, who won acceptance as king of both Picts and Scots. The MacAlpin kings took Strathclyde and Lothian into Scotland and Kenneth's male descendants provided kings for the next two centuries. The separate Pictish kingdom disappeared. All that remains are the beautiful carvings of weird beasts.