[citation needed] But, at several occasions during the Middle Ages or the Ancien Régime, new dioceses were created, replacing older ones or carved out of them.
For instance, the Albigensian Crusade entailed the creation of many new dioceses in the early 14th century.
All the same, in 1789, on the eve of the French Revolution, the ecclesiastical map of France still very much recalled that of Roman Gaul.
This explains why many dioceses and provinces did not coincide with French borders, with their head cities lying in present-day Belgium, Germany or Switzerland.
With the exception of those dioceses which were created in the Late Roman period (before the 6th century), whose date of creation generally cannot be established, we provide the date of creation and, when appropriated of suppression of the bishopric.