Although there is some evidence of early Christianization of the East Slavs, Kievan Rus' either remained largely pagan or relapsed into paganism before the baptism of Vladimir the Great in the 980s. The Christianization of Poland began with the Catholic baptism of King Mieszko I in 966. Slavic paganism persisted into the 12th century in Pomerania, which began to be Christianized after the creation of the Duchy of Pomerania as part of the Holy Roman Empire in 1121. The process was mostly completed by the Wendish Crusade in 1147. The final stronghold of Slavic paganism was the Rani, with a temple to their god Svetovid on Cape Arkona, which was taken in a campaign by Valdemar I of Denmark in 1168.