Within Old French many dialects emerged but the Francien dialect is one that not only continued but also thrived during the Middle French period (14th century–17th century).[30] Modern French grew out of this Francien dialect.[30] Grammatically, during the period of Middle French, noun declensions were lost and there began to be standardized rules. Robert Estienne published the first Latin-French dictionary, which included information about phonetics, etymology, and grammar.[34] Politically, the Ordinance of Villers-Cotterêts (1539) named French the language of law.
Хм, 16 век. Видать, бес таки попутал.
Ну, моя мысль была о том, что до этого были множество диалектов, вот как тот франкский, из которого французский и вышел. Так как стал доминирующим на этой территории.