 Harald's usurpation and his efforts at Christianization are related to several stories of "usurpation" and "changes in sacrifices", including the usurpation of Mithothyn and the introduction of the worship of Frey at Uppsala, in that they utilize similar motifs and mythical figures.The spread of Christianity in Denmark occurred intermittently.Danes encountered Christians when they participated in Viking raids from the 9th century to the 1060s.