Predominant? Only north of Perth. Rest of country spoke Ulster Scots/Lallans. In fact Welsh was even spoken up here. Unfortunately gaelic was pretty much eradicated due to the genocide of the highlands. There’s more polish speakers in Scotland than Gaelic speakers Id guess. And weegies can barely speak basic English.
Predominant in most of Scotland for a short time. It did spread into South Scotland in th 11th century. From wiki
In 1018, after the conquest of the
Lothians by the
Kingdom of Scotland, Gaelic reached its social, cultural, political, and geographic zenith.
[24]: 16–18 Colloquial speech in Scotland had been developing independently of that in Ireland since the eighth century.
[25] For the first time, the entire region of modern-day Scotland was called
Scotia in Latin, and Gaelic was the
lingua Scotica.
[26]: 276
[27]: 554 In
southern Scotland, Gaelic was strong in
Galloway, adjoining areas to the north and west,
West Lothian, and parts of western
Midlothian. It was spoken to a lesser degree in north
Ayrshire,
Renfrewshire, the
Clyde Valley and eastern
Dumfriesshire. In south-eastern Scotland, there is no evidence that Gaelic was ever widely spoken.
[28]
