The early medieval theme of Christianity's demographic expansion continued in the years between 900-1100. Christianity spread its fingers into Scandinavia, Poland, Bohemia, Hungary, and Slavic lands in Serbia, Bulgaria, and Russia. Around the 920s, Danes settling in England, as well as Vikings coming to Normandy, accepted the faith, and were integrated into the ecclesiastical structures of their host countries. Scandinavians remaining at home, though, only experienced Christianization during the process of state formation of the tenth century. Harold Bluetooth established a kingdom in Denmark and accepted the new faith in 960, recognizing the benefits of church hierarchies for an orderly state. The Norwegian Olaf Trygvesson had taken on Christianity while living in England, and patronized the religion back home after usurping the throne in 995. He encouraged English missionary work, and forcibly converted pagans. Olaf the Taxgatherer of Sweden converted around the same time, yet the regions population remained resistant to Christianity throughout the 1000s. Only by the early 1100s was the religion generalized in Sweden, with Uppsala receiving its own archbishopric in 1164.
In lands to the Saxon Empire's east, the crown took a direct interest in conversion. Poland, Bohemia, and Hungary were targeted. Bohemian dukes converted before 900, as Czechs were firmly within the fold by the 920s, receiving their first native archbishop in 982. In 968 Otto I established the Magdeburg archbishopric to further Polish conversion. The process did go forward, but local rulers were reluctant to accept German control. The Polish prince Mieszko (d. 992) married a Czech Christian princess, but did not want to be subordinate to the German churches. Otto III was prepared to accept this, and in 990, the prince put his lands directly under the Pope, yet still accepted German missionaries. As regards the Hungarians, after their defeat by the Germans at Lechfeld in 955, they began to form a unitary, stationary state, and accepted German missionaries sent by the Ottos. King St. Stephen (r. 997- 1038) firmly established the religion, making his realms directly subordinate to Rome. Thus, by the 1030s all these areas were Christianized. Further, the Bulgars accepted Christianity of the Eastern Orthodox rite by the 870s, just as Vladimir of Rus embraced the new faith for political reasons in the 990s, making his region's churches directly dependent on the Constantinople patriarch.
Beyond demographic expansion is the health of the religious institution. The ninth-century Papacy had reached a low point of spiritual decline. This malaise continued into the 900s, and the German emperors' nominees were only somewhat better. In general, the papal office became a prize over which Rome's noble clans fought. Popes were drawn mostly from aristocratic leadership. The worst example was John XII (956-963), deposed by Otto I. For the next century, popes either ascended to the position by German appointment when Germans dominated Italy, or through the uneasy consensus of the Roman urban nobility. The latter was more often the case, and their popes were actually poorer than the German candidates.
On the episcopal level, the Church also declined. Discipline and learning receded, as clerics were obliged to become part of feudal relations. Kings, as well as the more powerful feudal lords, began to appoint bishops, and protect churches. This entailed vassal-like responsibilities on the part of bishops and priests. Lay control over the church was often the result. Priests, who back- slid into clerical marriage, were often incorporated into the great feudal clans. These priests focused less on the religion than on using church property to support their family and feudal lord. A similar process affected monasteries. Based on the St. Benedict's rule, monasteries were independent of each other. Thus, monastic discipline depended on individual abbots. When these abbots became agents of powerful lords, political as opposed to spiritual criteria came to dominate their selection. At times, secular feudal lords acted as monasteries' titular abbots. Under such conditions, clerical positions could be viewed as revenue-producing positions. This opened the way to simony, the auctioning of church posts to the highest, and most often least qualified bidder.
By the 900s, some in church service were appalled by practices such as clerical marriage, simony, and general subservience to secular feudal leaders. In Burgundy, earnest monastics were able to convince William the Pious of Aquitane to found the Cluny monastery around 910. It was endowed generously from the start with relatively few strings attached, so that it would not be dependent on secular rulers. Additional gifts of land or provisions would not be in return for feudal services, but would be recompensed by the monks' prayers. Furthermore, the monks received the right to elect their own abbot, putting the position beyond lay interference. Additionally, Cluny's founders tried to eliminate any potentially idle time by instituting heavy schedules of communal liturgical prayer services, in addition to fieldwork and manuscript reproduction. Cluniac monks attained a high level of sustainable piety and discipline throughout the tenth century and into the eleventh. What's more, Cluny-based monasteries proliferated throughout France and Western Europe. To maintain effective supervision and unity of praxis, the order only had one abbot, with other houses ruled by priors subordinate to him. By the time of the great abbot Odilo (994-1048), the original Cluny compound had 300 monks, in addition to more than 150m dependencies. These dependencies were allowed to have lay patrons, who were often kings. Cluniac monasticism entered Germany from the early 1000s, with Conrad II (r. 1024-1039) supporting them, though he did oppress his native clergy. His son Henry III (r. 1039-1056) actually viewed himself as the order's protector and patron, lending momentum to the eleventh century 'reform party' in the Church. Ultimately, alumni of Cluny entered the 'secular' church's hierarchy, as well as the papacy. Reflecting this trend is the eleventh and twelfth century attempt on the part of the Church to curtail violence in feudal society. Councils proclaimed the Truce of God, whereby fighting on religious holidays was proscribed. The Peace of God prohibited attacks on non-combatants, such as women, children, merchants, peasants and priests. It is not clear that these prohibitions were heeded at all, but it established the Church's position on the moral high ground. Also significant were the reforming popes. They would articulate the idea of a papal monarchy entitled to temporal powers for the sake of spiritual betterment of Europe. In the process they would come into direct conflict with the German patrons of the clerical reform movement.
Between 1046 and 1049, Henry III of Germany had appointed a string of Popes. His last, Pope Leo IX (1049-54), was tremendously significant. A cousin to the Emperor and a bishop in an important reforming German diocese, Leo's major achievements are two.