Like many countries, France has it's share of ethnic diversity. They have everything from gypsies to Mennonites, and if you are looking for what region an ancestor may have come from, begin with their ethnic background.
Many of the Jews came from Alsace, Protestants from France, and Mennonites from Lorraine. If you want to search for any of these minorities, check under the headings of Huguenots, Jews, Germans, Mennonites in conjunction with French Minorities!