The origin of the Crusades has its roots in political upheavals. The mid-7th century and mid-10th century CE saw a gradual expansion of Islam (Riley-Smith 1). Half of the Christian world was conquered by Arab armies. This included countries where Christianity had been established for centuries, such as Egypt, southern France, southern Italy, Sicily, Spain, Syria, and Turkey (Riley-Smith 2). By the end of the 10th century, Europe and the Middle East were divided into Christian and Muslim hemispheres of influence. Christian pilgrims from Europe regularly visited Muslim-controlled Jerusalem. These pilgrimages were very popular. Christians believed that pilgrimage was an important act through which a person could reduce their exposure to the tortures of purgatory after death (Asbridge 21). Islamic forces had overwhelmed the Iberian Peninsula in 711 AD. The advance was so strong that only the might of Charlemagne's grandfather, Charles the Hammer, was able to push them back from the borders of France and the heart of Latin Christendom (Asbridge 17). The Muslims left the Christians only a small slice of territory in the north. The kingdoms of Western Europe were vaguely described as “feudal” (“Crusades”). Although the Latin states were still behind other civilizations along the Mediterranean basin, Western Europe had amassed a considerable amount of power by the 11th century (“Crusades”). The First Crusade was preached by Pope Urban II on November 27, 1095 in Clermont, France. In this sermon, Pope Urban II reformulated the concept of “sanctified violence” in a devotional format that was familiar, convincing, and attractive to the populace (Asbridge 37). The Pope preached a sermon of salvation to the Christians....... middle of paper ......nline Encyclopedia." Encyclopedia - Britannica Online Encyclopedia. Web. 25 March 2011. .Foster, M. "Antioch - Una brief history of the crusades." Medieval Crusades Splash/Home Page. Web. March 25, 2011. .Hickman, Kennedy. "Siege of Jerusalem - Siege of Jerusalem of the Crusades 1099." Military History - Wars Through the Ages - Battles and Conflicts - Weapons of War - Military Leaders in History. Web. 25 March 2011. Riley-Smith J. Oxford Illustrated History of the Crusades. Oxford University Press, Oxford, pp. 1 -2, 2001. "Siege of Nicaea, May 14 -June 19, 1097." Encyclopedia of Military History on the Web. Web. March 25. 2011. .