The vast majority of the population however spoke a variety of vernacular languages derived from vulgar Latin, the common spoken language of the western Roman empire. The medieval Italian poet Dante, in his Latin De vulgari eloquentia, classified the Romance languages into three groups by their respective words for "yes": Nam alii oc, alii si, alii vero di
oil, "For some say oc, others say si, others say oïl". The oïl languages – from Latin hoc ille, "that is it" – occupied northern France, the oc languages – from Latin hoc, "that" – southern France, and the si languages – from Latin sic, "thus" – the Italian and Iberian peninsulas. Modern linguists typically add a third group within France around Lyon, the "Arpitan" or "Franco-Provençal language", whose modern word for "yes" is ouè.
The area of langues d'oïl
The Gallo-Romance group in the north of France, the langue d'oïl like Picard, Walloon, and Francien, were influenced by the Germanic languages spoken by the Frankish invaders. From the time period of Clovis I on, the Franks extended their rule over northern Gaul. Over time, the French language developed from either the Oïl language found around Paris and Île-de-France (the Francien theory) or from a standard administrative language based on common characteristics found in all Oïl languages (the lingua franca theory).
Langue d'oc, the languages which use oc or òc for "yes", is the language group in the south of France and northern Spain. These languages, such as Gascon and Provençal, have relatively little Frankish influence.
The Middle Ages also saw the influence of other linguistic groups on the dialects of France:
From the 4th to 7th centuries, Brythonic-speaking peoples from Cornwall, Devon, and Wales travelled across the English Channel, both for reasons of trade and of flight from the Anglo-Saxon invasions of England. They established themselves in Armorica. Their language became Breton in more recent centuries.
Attested since the time of Julius Caesar, a non-Celtic people who spoke a Basque-related language inhabited the Novempopulania (Aquitania Tertia) in southwestern France, while the language gradually lost ground to the expanding Romance during a period spanning most of the Early Middle Ages. This Proto-Basque influenced the emerging Latin-based language spoken in the area between the Garonne and the Pyrenees, eventually resulting in the dialect of Occitan called Gascon.
Scandinavian Vikings invaded France from the 9th century onwards and established themselves mostly in what would come to be called Normandy. The Normans took up the langue d'oïl spoken there, although Norman French remained heavily influenced by Old Norse and its dialects. They also contributed many words to French related to sailing and farming.
After the conquest of England in 1066, the Normans's language developed into Anglo-Norman. Anglo-Norman served as the language of the ruling classes and commerce in England from the time of the conquest until the Hundred Years' War,[5] by which time the use of French-influenced English had spread throughout English society.
