Occitan (Occitanian, oc language, Gascon), in its Gascon variant (Aquitaine). It is the most spoken regional language in France, with perhaps 4 million speakers. An Occitan poem, in the language of troubadours and Gascon musketeers! Alexandre Dumas's Three Musketeers ... Here's a nice reference.
It was after the classicism of the troubadours that a koiné administrative (14-15th) was constituted. The former Occitan is distinguished from the old French by its more conservative character, a deeper romanization and a weaker Germanization. There are three dialectal groups (Limousin, Auvergnat, Dauphinois), (Languedoc, Provencal), and Gascon in which certain linguists see a particular language. In literature, it is in Limousin that we first find a poem about passion (10th), others on Boethius (11th), lyrical poetry to the virgin, and also profane poems, the oldest Are the Guillaume 9's songs. The troubadours's poetry will be followed by hundreds of poets (and the greatest) who will be at the origin of courtly love. The principal representatives of this poetry are Bernard de Ventadour, Jaufré Rudel, Arnaut de Mareuil etc ... Under Aliénor d'Aquitaine will propagate all this poetry and this until the Albigensian crusade. From the 13th century, Provencal literature declines in spite of the "bourgeois poets". The historical poetry of the "song of the crusade against the Albigensians", and the epic poetry will remain the two poetic genres. In the 16th century, great truculent poets like Bellaud de la Bellaudiere, Ruffi, Tron, Garros, Du Bartas and especially the Malherbe of the Oc language Pierre Goudelin (Goudouli) will bring literature back to life. We shall find at this period a crowd of poets, speaking in the various Provencal dialects, which will make exist Oc poetry. In the 18-19th century, Mistral, the great figure, Rieu the popular poet, the great Valère Bernard, and Baroncelli-Javon will be among the most noted.