 The strengthening of the power of the papacy was very important from Pope Gregory I on, and depended on the support of the monastic orders, above all the Order of Cluny.The constitution of many of these new kingdoms made them feudally obligated to the Pope, which liberated them from the theoretical feudal subjugation of the emperor or another king (such was the case of Portugal).In the territory of the Sacred Empire, the rivalry between the Guelphs, supporting the Papacy, and Ghibellines, supporting the Emperor, dominated German and Italian political life from the 12th to the 15th century.