[orwin]

You're reversing the causes and effect here. The basque did not have any issue being divided between 3 kingdoms for a thousand years. Breton did not mind being ruled by Gallo for at least as much time. Somehow, they started revolting when the state, the nation rather, started imposing their own languages and forbidding them to keep their cultural identity. Everybody talk about the Armenian genocide, but this is only the last of a long history, the 19th century is riddled by ethnic displacement to make the nice looking european border match the ethnicity. Italy did exactly the same, Austro-Hungary too. The Balkan crisis is caused by an ethnonationalism the did not exist before.

You know that have multiple culture in your kingdom was a sign of strength until the end of the 18th century, right? Despite the Villers-Coteret directive, nothing could please a King of France more than listening the his multilingual, multicultural country. It is really obvious than the cultural area we have no were forced. I know there is a lot of fear behind the sinicization, but France did the same in less than 50 years, although at a smaller scale, with a modicum of violence and some small concessions.

Aragon was probably one of the most multicultural, multilingual kingdom of old, but since the concept of nation did not exist, and that ethnicity was just another word for language 95% of the time, it did not cause any issue, and certainly not ethnic tensions.