Quote Originally Posted by castledangerous View Post
Well, that depends on how far back you are considering. If you went back before the Anglo-Saxon invasions, then there certainly would have been a time when Scottish Gaelic (Gàidhlig) was the chief language. For example, "Scottish Gaelic was spoken throughout Scotland (apart from small areas in the extreme south-east and north-east) between the 9th and 11th centuries...." from http://www.omniglot.com/writing/gaelic.htm
The Anglian kingdom of Bernicia was established in the southeast of what is now Scotland in the mid-6th century. At that time the kingdom of the Scots (Dalriada) was a pocket on the west coast. Scottish Gaelic became the chief language of what is now Scotland between the 9th and 11th centuries, when the kingdom of the Scots absorbed the Picts and then began to project its influence south of the Forth. Both English and Gaelic are relative newcomers that displaced the older languages of what is now Scotland: Pictish, north of the Forth, and Cumbric (related to Old Welsh) to the south.

Scottish Gaelic, along with Norman French (!), was the courtly language of Scotland during the High Middle Ages. At this same time the courtly language of England was Norman French. These courtly languages died out in England and the Scottish Lowlands simply because the nobility and their retinues were surrounded by large numbers of English-speaking commoners, including the increasingly influential townspeople and traders. This process took place centuries after the initial Anglo-Saxon invasions.