French Flanders is a part of the historical County of Flanders, where Flemish—a Low Franconian dialect cluster of Dutch—was traditionally spoken. The region lies in the modern-day northern French region of Hauts-de-France, and roughly corresponds to the arrondissements of Lille, Douai and Dunkirk on the northern border with Belgium. Together, with French Hainaut and Cambrésis, it makes up the French Department of Nord.
Territorial changes due to the Treaty of the Pyrenees (1659), including French Flanders