is the most differentiated Breton dialect. According to a 1999 INSEE survey, 12% of the adults of Brittany speak Breton. Gallo Gallo is spoken on the eastern half of Brittany. It is not itself a Celtic language. Like French, it is also descended from Latin (and is classified in the Langues d'oïl branch), but has some Celtic influences, particularly in its vocabulary, whereas French has influences from both Celtic (Gaulish) and Frankish (the Germanic language which arrived after Latin in much of the rest of France). Unlike Breton, Gallo does not have a long promotion history and it is still often perceived as a poor rural dialect. Moreover, because of its linguistic relationship with Gallo, French imposed itself more easily as the main language in Upper Brittany than in Breton speaking areas. Gallo was simply felt to be an incorrect way of speaking French rather than a separate language. Gallo transmission from parents to children is extremely low and efforts to standardise and publish books in Gallo did not reverse the decline of the language and its lack of prestige. Gallo is also threatened by the Breton language revival, because Breton is gaining ground in territories that were not previously part of the main Breton-speaking area, and most of all because Breton appears as the national language of Brittany, thus leaving no place for Gallo. Gallo had never been written before the 20th century, and several writing systems were created. They are however rarely known by the population and signs in Gallo are often unreadable, even for fluent speakers. In Loire-Atlantique, where Gallo is not promoted at all by the local authorities, many people do not even know the word "Gallo" and have no idea that it has writing systems and publications. The Gallo community is estimated at between 28,300 and 200,000 speakers. The language is taught on a non-compulsory basis in some schools, high-schools and universities, particularly in Ille-et-Vilaine. Religion Bretons are mainly Catholic and the Christianisation occurred during the Roman Gaul and Frank era. During the Briton emigration to Brittany, several Christian missionaries, mostly Welsh, came in the region and founded dioceses. They are known as the "Seven founder saints": Paol Aoreliann in Saint-Pol-de-Léon, Tudwal in Tréguier, Brieg in Saint-Brieuc, Maloù in Saint-Malo, Samsun of Dol in Dol-de-Bretagne, Padarn in Vannes, Kaourintin in Quimper. Other notable early missionaries are Gildas and the Irish saint Columbanus. In total, Brittany