Even before the Gaelic Christian monks arrived around 500AD from Ireland in Iona, the Celtic Scotti (Scots) - meaning  raider, a term coined by the Romans - had already been infiltrating the south west of Scotland since around 350. It would be at least another century before settlement really began in earnest, with the arrival of King Fergus Mor in c500 AD. Communication was certainly established between the Irish tribes and the  Pict’s of Northern and Eastern Scotland by the year 367, as both launched assaults on Roman Britain in that year.

Map of Dalriada

Scots Kingdom of Dalriada

The kingdom of Dalriada or Dál Riata as it was known in Ireland, was to see its power in Ulster greatly diminished by a decisive defeat by the O'Neill's (Uí Néill) in 637AD at the Battle of Mag Rath. From then on the Dalriadans focused on their lands in what is now Scotland. Their rivals were the Picts to the north and north east the Britons in the south west and the Angles to the south east. On the south they were bordered by Strathclyde, a Brythonic kingdom. Dunadd, in north Lochgilphead, Argyll, was probably the seat of the kings of Dalriada. It has been excavated and in addition to fortifications many moulds for the manufacture of jewellery were found. A census of Dalriada exists, the Senchus fer n'Alba.
Raids by the Scoti (Scots) of Dalriada also spread to parts of Wales as they made attempts to invade its southern part, but the Welsh ruthlessly and efficiently crushed the attempts. The Welsh have a natural defensive barrier on much of their western borders



Dalriada Kingdom at the height of its power



Later, this would also hinder the Vikings from truly colonising Wales. Perhaps some evidence of these attacks was recorded on the Ogham, Turpillian Stone of Crickhowel where upon the name Dunocoati - Duncotus (Duncan) is recorded. 
One of the Kings of Dalriada in western Scotland was Dunchad (Duncan) mac Conaing who co-ruled Dalriada with Conall II (c. 650 - 654). He was defeated and killed by Talorcan mac Enfrith, king of the Picts, in a battle at Strath Ethairt. 

Although there were numerous battles between the Picts and Scots the Kingdom of the Dalriada was to expand eastward into what came to be known as the Forest of Atholl and Strathearn (from the river Earn) and northward into the area of Elgin. The union of the lands of modern Scotland began in 843, when Kenneth MacAlpin, then King of Dalriada was to start the unification of the four kingdoms of Northern Britain and the birth of a single united nation of Alba (Scotland).


Entrance to the Hill Fort of Dunadd

Dalriadian Jewellery Moulds form Dunadd Fort


The 'Stone of Destiny' Coronation seat of the Kings