In the 16th century, the Protestant Reformation caused great change in the religious and political life of Geneva. Prior to the reformation, the Diocese of Geneva extended well into Savoy, as far as Mont Cenis and the Great St Bernard Pass. It also included Nyon. However, under the rule of Charlemagne (742 - 814) Tarantaise was detached from Geneva to form a separate diocese. The bishops of Geneva ruled over 8 chapters, 423 parishes, 9 abbeys and 68 priories.