I know that Occitan is the first language that had its own literature apart from Latin in Europe after the fall of the Roman Empire. And my question is: Throughout the Middle Ages, how important was this language in Europe? Was it considered as a sort of language of prestige?
Troubadors were writing and singing their songs in it: that's pretty important. But though Provence is now reviving it, and is/was a pretty distinct region, Occitan was quite widespread. Dialects were spoken in lots of France that wasn't dry and sunny; like Limousin, and until the end of the Hundred Years War a portion of Occitan-speaking France was in the hands of the English, coming with the marriage of Eleanor of Aquitaine ( who liked troubadors) to Henry II. Catalan is also in the same language family, which makes it perhaps even harder to generalize about Occitania as a country. You're likely better off getting a good history of France.
Also, do you know any good book about the history of Occitania?