Abstract The presence of francos settlers in Navarre and Aragon left abundant administrative and legislative documentation in the Occitan language. This presence of settlers of different origins, both lengua d’oc and lengua d’oïl, with also differentiated dialectal modalities, who carried out commercial activities, produced intense linguistic contact between the different dialectal modalities. The paper tries to determine the type of language reflected in the aforementioned administrative and legal documents, which use the graphic system of the scriptae of Navarre and Aragon, conveying the romance varieties. Although the term koine has been used to define this language, the concept of koineization more adequately defines the dynamic process of leveling and blending of dialects, whose formation of a stabilized koine may be one stage. Thus, within the scriptae of Navarre and Aragon in the Occitan language, different linguistic norms and stable as well as diffuse language varieties can be identified.