to my understanding, the times when germany and italy began to fracture were in the wake of the carolingian empire, with entities (almost entirely the HRE, right?) almost immediately afterwards granting fiefs to vassals to the extent that germany and parts of italy came to look a lot like a jackson pollock painting. it then took several centuries seemingly for a sense of regional nationalism to supersede past boundaries such as language

so my question(s) are this: given the fact that france itself had its fair share of cultural dissonance- between the paris-centered langues d'oïl, the occitan, and a fair amount of basque, arpitans, catalans, and bretons, how did france manage to generally not be split between multiple messy duchies for most of its history in the same way that germany and italy did?