section_path: Probable causes/Ideological model
section_name: Ideological model
paragraph_text: Ideological model
  
  This era coincided with the Medieval Warm Period (800–1300) and stopped with the start of the Little Ice Age (about 1250–1850). The start of the Viking Age, with the sack of Lindisfarne, also coincided with Charlemagne 's Saxon Wars, or Christian wars with pagans in Saxony. Bruno Dumézil theorises that the Viking attacks may have been in response to the spread of Christianity among pagan peoples. Because of the penetration of Christianity in Scandinavia, serious conflict divided Norway for almost a century.