Albigensians – Wikipedia

The Albigensian Crusade (French: Croisade des albigeois) or Cathar Crusade (1209–1229) was a military and ideological campaign initiated by Pope Innocent III to eliminate Catharism in Languedoc, what is now southern France. The Crusade was prosecuted primarily by the French crown and promptly took on a political aspect. It resulted in the significant reduction of practicing Cathars and a realignment of the County of Toulouse with the French crown. The distinct regional culture of Languedoc was also diminished.
— Read on en.m.wikipedia.org/wiki/Albigensian_Crusade