Occitan speaking Poitou, Liguria, Arpitania and Piedmont, how would that effect italy and france?
Poitevin and Arpitan have Occitan substrate, Ligurian and Piedmont have occitan influence.Poitou could actually remained Occitan-speaking given the right circumstances; after all, Poitevin has an Occitan substrate.
Occitan speaking Poitou, Liguria, Arpitania and Piedmont, how would that effect italy and france?
You need to be a little more specific, and I think you've got it arse about face. Languages don't just happen to be in places, the Latin dialects spoken in the areas are parts of a continuum with Occitan. For Liguria and Piedmont to speak Occitan you need there to be an Occitan political power over them which causes their dialects to accommodate towards Occitan rather than Florentine as OTL.
In this situation there would be a very different Italy and France.
Possible solution: William the Conqueror attacks Paris instead of England, which is used by the nobility in southern Frabce to become independent.The southern border of this greater Normandy would be the Loire, while Occitania could become a major power as this may butterfly the Albigensian crusade and Bartholomew night.Catalonia may be considered culturally Occitan, and perhaps Occitan influence could be projected over the Alps
"Occitania" is not a polity. You had the Duke of Aquitaine, the Count of Toulouse, the Count of Barcelona and the Count of Provence, all competing for power between themselves and with local lords. Before any cultural extension, you would need political union, quite difficult given the chaos that would follow the desintegration of the French Kingdom.
Considering that Poitou used to speak Occitan until the early modern period and indeed was under the Duchy of Aquitaine, it shouldn't be too impossible. You'd just need something to sever the connection between Paris/northern France and the rest of modern France, which would take a very early POD.
I wonder if you could conceivably have a "South Francia" which would indeed consist of those territories, whereas we'd compensate West Francia by giving it most of the relevant Middle Francian territories.
There would have to be a different division of the Carolingians leaving a surviving Kingdom of Aquitaine.Who would create such an entity ?
Actually, having just Dante write Divina Comedia in occitan not tuscan might work as POD..Imho having Provence united to Northern Italy will Occitanize Northern Italy not the other way around since occitan was the linguafranca there at one point, a reformation pod can also work have protestant occitans go to piedmont.There would have to be a different division of the Carolingians leaving a surviving Kingdom of Aquitaine.
For Piedmont and surrounds to speak an OccitanoRomance (rather than Occitan specifically) a possible surviving Arelat might do. It'd be a form of Provencal which became rather popular in the high middle ages (assuming that popularity isn't butterflies away).
Dante wrote in Tuscan as he was a Florentine and the Florentine dialect was close to but less prestigious than Tuscan.Actually, having just Dante write Divina Comedia in occitan not tuscan might work as POD..Imho having Provence united to Northern Italy will Occitanize Northern Italy not the other way around since occitan was the linguafranca there at one point, a reformation pod can also work have protestant occitans go to piedmont.