The influence of French in the Croissant zone goes back a long way. The presence of French-speaking nobility and administrators caused, from the second half of the 13th century, administrative and legal documents to be written in French and not in the local dialects, as well as in
Marche County (
Limousin-speaking territory) and in
Bourbonnais (
Auvergnat-speaking territory). In Bourbonnais, the earliest known documents written in the local vernacular are deeds in French with some
Occitan forms inserted from 1245. Therefore, the Croissant has been a Langue d’oc-
Langue d’oïl diglossia since that time, long before French had spread through the rest of the Langue d’oc linguistic area. The border between Langue d’oc and [Langue d’oïl was once located further north and has moved southward over the centuries. The French dialects the north of the Croissant (the southern part of
Berry and the northern part of Bourbonnais) still contain traces of the Langue d’oc substrate. The spread of French towards the Croissant has been a long and progressive process, in contrast to the quite rapid
désoccitanisation of
Poitou,
Saintonge and
Angoumois, which took place between the 12th and 15th centuries, principally from the ravages of the
Hundred Years' War, which caused the area to be consecutively repopulated. In the Croissant dialects, the spread of Gallicisms has increased, weakening the local Occitan variants. During the last few centuries, it seems that progression to have been more rapid in
Marche County (
Limousin-speaking territory) than in Bourbonnais (
Auvergnat-speaking territory). However, since the 20th century, in all cases, the spread of French has resulted in a
diglossia, and linguistic substitutions similar to those across all of the Langue d’oc regions. That puts into perspective the "gallicised" aspects of the Croissant dialects today since nearly all Occitan dialects are undergoing a process of Gallicization. ==Dialectological subdivisions==