There are several good histories of Scotland, but that website little john listed is long on rhetoric and short on facts. Fergus mac Roch (Fergus Mor in that website history) wasn't the first of the Scots (as the Irish were called then) to arrive in Kintyre (in 503 CE). There had already been a small group there, but no one knows for how long. Estimates run up to about 200 years. Fergus mac Roch is mentioned in a Mabinogion tale as a (distant) ally of King Arthur.

Gerald of Wales said the inhabitants of Ireland were called Scots because they were all descendents of a Spanish princess called Scotia. [Does this make all Irish black Irish?]