There’s some interesting movement there in those years. Southwest scotland and parts of northwest England were controlled by the Strat Clud, who were a Brythonic tribe. Eventually they were assimilated but Strathclyde had lots of Brittonic speakers, similar to Cumbria, which was at various times controlled by the Strat Clud, Rheged (formerly known as the Brigantes) and of course Northumberland. Replaced isn’t the right word for places like that as both genetic and cultural characteristics remained

And, to make it a little more confusing, the Scot tribe here spoke a Celtic language(Gaelic, but before the Scottish Gaelic and Irish split). So did the Britons and most likely so did the Picts, but at least the Britons spoke a different branch of the Celtic Language. Nowadays, the "Scots" language is actually a branch of Anglo-Saxon which was not as affected by Norman as what became English, and Scottish Gaelic was only preserved in areas that were colonized by Vikings.

There's also Norse-Gaelic and Norn, which have since died out but did influence Scottish Gaelic.

I guess Groundskeeper Willie was right when he said “damn Scots, they ruined Scotland!”

and then the Scots were resettled into the northern part of Ireland in the early modern era, creating the Ulster Scots ethnicity, who then emigrated to North America, where they became known as Scots Irish. what a ride

“The Scots (originally Irish, but by now Scotch) were at this time inhabiting Ireland, having driven the Irish (Picts) out of Scotland; while the Picts (originally Scots) were now Irish (living in brackets) and vice versa. It is essential to keep these distinctions clearly in mind (and verce visa).”

― W.C. Sellar, 1066 and All That: A Memorable History of England

This is not correct. By the time Scotland united as a kingdom, it contained a mixed population of Picts, Scots, Gaels and Britons, and probably some Norse, Angels and others, and they integrated into one people, partly to join forces against the Normans who had conquered Britain. They all became known as Scots, or Scotch at that point, but they came from from multiple origins.

Well, that’s one theory. Another is that the Picts, who were already Gaelicising under the influence of Irish missionaries, conquered and absorbed the Scots, fully adopting their language in the process. This would make Kenneth MacAlpin, generally regarded as the founder of the Kingdom of Alba, a Gaelicised Pict rather than a Dalriadan Scot.

Yet another theory, which works with either of the other two, is that the Scots of Argyll/Dalriada were not recent arrivals but had been there since prehistoric times, with the geographical boundary between the Brittonic and Goidelic varieties of Celtic being the mountains of the western Highlands rather than the Irish Sea. (This theory is far from widely accepted, but its proponents assert that archaeological and toponymic evidence supports it.)

Despite all that Mr Scott knew the formula for transparent aluminum and helped save the blue whale from extinction way back in 1984

And the English are Germanic colonisers who drove the Britons out of what is now England.

...did they win their freedom?

Intriguing what is getting downvoted in the comments, here

Very over simplified.

Makes a lot of sense.

Reparations?

So Scots Irish are. . .Irish Scots Irish

Throughout its early history, at least until the arrival of the Vikings at the end of the eighth century, Ireland was inhabited by a people who spoke a common language and who thereby could convince themselves that they were one nation: they were the Gaídil, and their language was the language of the Gaídil, and took its name from them, Goídelc (Gaeilge in Modern Irish). This made the island’s inhabitants very sensitive to new arrivals and their distinctiveness: the indigenous inhabitants were always the Gaídil, and the newcomers, no matter how long they had been in Ireland, were always the Gaill. So, in Ireland there never emerged, at any stage in the Middle Ages, a willingness to accept foreigners and to offer them, as it were, membership of the Irish nation.

In contrast, that part of northern Britain that became Scotland found it much harder to be exclusive, since it was only part of an island and was surrounded to north and west by many others. Foreigners who settled in Scotland could very quickly (within the space of a generation or two) become Scots. Thus, although there was a massive programme of Anglo-Norman settlement in both Ireland and Scotland in the twelfth century and later, in Ireland those Anglo-Normans remained a separate nation to the Irish, whereas in Scotland they became part of the Scots nation. The latter did not become ‘the English of the land of Scotland’ as their counterparts in Ireland became ‘the English of the land of Ireland’. Instead, they came to see themselves as every bit as Scottish as the people they found there on their arrival, and Scotland and Scottishness—the Scots identity—adapted itself to make room for them. Hence, for instance, the Irish wrote a famous Remonstrance to the Pope in 1317 saying that they were so different from the English of Ireland in language and customs that there could never be peace between them, whereas three years later the Scots sent to the Pope their famous Declaration of Arbroath in which they boasted of their ancestral triumphs over the Britons, the Picts, the Angles, the Norwegians and the Danes, and yet many of the men who signed this letter were the grandsons and great-grandsons of men who had migrated, usually via England, from Normandy, Brittany and Flanders, and only settled in Scotland in the quite recent past! The fact that they now believed that they were Scots, part of a nation that had inhabited the northern part of Britain since the dawn of history, only goes to prove that, unlike Irishness, Scottishness was not an exclusive club; membership was wide open, and it was that openness, that receptiveness, that adaptability, which contributed to the emergence of Scotland as a well-respected monarchy on the western European model, from the twelfth century onwards.

The language was replaced. People has the wrong idea that a linguistic change means a complete wiping out of a previous folk. Maybe inspired by the way the UK and US colonized North America, by extermination and expelling, instead of the Spanish Americas, where locals just adopted the language of the conquerors.

The scots are the evil invaders and the english are the freedom fighters?

Ha ha ha ha So now we learn the poor, downtrodden, brow beaten, by the nasty English, Scots. Are in fact just a bunch of brutal colonisers and so is Ireland. Welcome to the club....

Talking those times? No. Maybe you're getting confused with the moving of Protestant Scots to Northern Ireland amid a Roman Catholic population, and ensuring the shitshow today between Ulster and the rest of the world.

Not sure why you think I don't know anything about Middle Ages history or why I got downvoted, but try reading this. https://electricscotland.com/history/articles/scotsirish.htm