Medieval Pomerania was converted from Slavic paganism to Christianity by Otto of Bamberg in 1124 and 1128 (Duchy of Pomerania), and in 1168 by Absalon (Principality of Rügen).
Earlier attempts at Christianization, undertaken since the 10th century, failed or were short-lived. The new religion stabilized when the Pomeranian dukes founded several monasteries and called in Christian, primarily German settlers during the Ostsiedlung. The first Pomeranian abbey was founded in 1153 at the site where the first Christian duke of Pomerania, Wartislaw I, was slain by a pagan. The Duchy of Pomerania was organized by the Roman Catholic Church in the Bishopric of Cammin in 1140. Pomeranian areas not belonging to the duchy at this time were attached to the dioceses of Włocławek (East), Roskilde (Rügen) and Schwerin (West).