During the 1300-1400s, there were many little states in France, including Burgundy, Provence, and Brittany.
Which weren't exactly "little states" at this point. By the XIIth century, the royal hegemony over France was established.
Hegemony doesn't mean, of course, direct domination. But it was unquestionably the king that was the most important political force of the kingdom.
Even these feudal states had to acknowledge this, and would it be only trough sheer political interest (but as well, trough a whole ideology that made them inclinded to do so*) act in this sense.
These entities, safe in very precise context in Late MA, never went against (or at least openly) this royal hegemony but merely wanted to either be part of this influence (Armagnacs after the HYW) or to be left alone (Brittany).
This is to be stressed : they weren't, even from the start, independents. They were largely autonomous, up to the point not having to care with royal decisions, BUT were still tied up to vassality structures.
It wasn't just a question of formalism : not only denying it would have lead to deligitimize themselves (their power was issued from royal decision, at least symbolically**) but to let their own vassals free to do the same with you.
It became more and more irrelevant in the Late MA, because of the bureaucratisation and unification of feudal entities but at this point, royal hegemony did became royal domination in France.
*Medieval ideologies are for some kind of reason, totally ignored when it come to political structures on this board.
** And for anyone that knows about the strength of symbol in medieval society, that means a lot.
kill off the Capets early. keep Occitan France separate/unite it with Aragon. wank the Bretons. wank Navarre.
prevent the Albigensian Crusade, it weakened Aragon and forced Toulouse into the sphere of the kingdom of France.
Try and get Eleanor of Acquitaine married to the Count of Toulouse instead of Henry II.
I'm afriad that I have to disagree, strongly, with this. Allow me to explain why.
First, I don't think you really have a good idea about how southern France looked like politically. It was a mess of principalties, themselves desintegrated into smaller entities, etc. You didn't have any Occitan (which is, historically, defined by Capetian politics, in order to distinguish their demesnes in Languedoc from Aquitaine. Occitan means exactly this, Languedoc, "Òclanguage") identity.
The Count of Toulouse had barely any power in Albi, for exemple, while it was a viscounty of them. Merging two particularly desintegrated principalities is not going to help : at best it would make the situation unchanged, at worst it would make it even more chaotic.
Or Trencavel plundering Besièrs decade after Crusaders did so, because the count was murdered by urban patricianship.
Heck, after the revolution of 1189, Toulouse itself was basically akin to contemporary Italian city-states.
Then this mess was a hive for perpetual wars. I mentioned earlier you didn't have any Occitan identity politically-wise. Basically, it was a HYW with 4 players : Aquitaine/Plantageners, Toulouse, Trencavel and Barcelone/Aragon, and so at least since the War of Succession of Aquitaine in the Xth.
Not only strategic matrimonial alliances aren't a CKII-like feature that can happen between anyone for no good reason, but even when it happened IOTL, it never went trough a pacification of the region.
It was why Toulouse entered within Capetian sphere much before the Crusade : Raimond V married a Capetian princess, and beneficied from royal support against Henry II's ambitions on the county (that were directly issued from Aquitain ones).
In order to strengthen the region, you'll need to go as far back than Carolingian period, maybe Late Carolingian period. After the death of Acfred of Aquitaine***, and the end of Guilhemid line, it only went downhill as for political unity.
***I'd even say that you'd have to work with William I having sons
Anyway.
In order to "balkanize" France as much as possible in the XIVth/XVth century, you'd need to butterfly away Lancastrian conquests. It seems a bit weird, but it would have allowed the reinforcement of principalties as Bourgogne, Brittany, Foix, Armagnac, etc; while the war forced Valois to undergo a fiscal, military, administrative and eventually political unification.
Let's be straight : even at this point, these principalties acted not independently as if there were no supreme political power, but more as landed factions. Still, their survival *could* make France looking a bit more as HRE.
The Orléans/Armagnac - Bourguignon civil war, after all, was not a nobiliar war, but a civil war with nobles or population siding with one or the other (Paris was a famous Bourguignon city, while not Burgundian territorialy or politically)
Eventually, with a continued apanage policy, with Valois unable to retrive all of them or unable to fully enforce their rule (IOTL, these lands were pretty much under royal scrutiny. But in an ATL were it's more chaotic, you could see attempt à la Louis XI when he was dauphin, and
apanagiers nobles gaining more autonomy.
I doubt it would remain like that even IATL with a PoD in the XIVth/XVth century. In fact, I'm kind of skeptical it will.
But it would be a good step for having more political autonomy lasting ITTL up to nowadays.
But if you want no France at all...Giving that unifications trends date as back as the Merovingian Era, you'd need a Late Antiquity PoD.