 After the departure of the Romans from Northern Britain , in the fifth century four major circles of influence had emerged in what is now Scotland . In the east were the Picts , whose kingdoms eventually stretched from the river Forth to Shetland ; in the west the Gaelic ( Goidelic ) -speaking people of Dál Riata with their royal fortress at Dunadd in Argyll , with close links with the island of Ireland , from which they brought with them the name Scots ; in the south was the British ( Brythonic ) Kingdom of Alt Clut , descendants of the peoples of the Roman @-@ influenced kingdoms of " The Old North " ; finally , there were the Angles who had overrun much of southern Britain and held the Kingdom of Bernicia ( later the northern part of Northumbria ) , in the south @-@ east . This situation was transformed from the eighth century when ferocious Viking raids began . Orkney , Shetland and the Western Isles eventually fell to the Norsemen . These threats may have speeded a long term process of gaelicisation of the Pictish kingdoms , which adopted Gaelic language and customs and which probably facilitated a merger of the Gaelic and Pictish crowns . This culminated in the rise of Cínaed mac Ailpín ( Kenneth MacAlpin ) in the 840s , which brought to power the House of Alpin , who became the leaders of a combined Gaelic @-@ Pictish kingdom , known as the Kingdom of Alba and later as Scotland . 
