Owing to the influence of conquests by both Islamic and Christian rulers, polytheism continued to decline into the Middle Ages. Islamic armies suppressed cruelly and immediately a rebellious movement of apostasy that spread through Arabia after Mohammed’s death. Polytheism likewise had already vanished in North Africa and other parts of West Asia, conquered by Muslims, because these were regions that had previously been strongly Christian. Only the fringes of Europe remained in the old ways, but that was to change gradually. Various crusades were waged against polytheists in Europe, who were viewed as polluted and lost souls that required either guidance or death. In those distant places, instances of noble resistance and vile treachery are known.