The causes of the Crusades were many and complex, but prevailing religious beliefs were clearly of major importance. The Crusaders continued an older tradition of the pilgrimage to the Holy Land, which was often imposed as a penance; now, however, they assumed a dual role as pilgrims and warriors. Motives for crusading in addition to regaining the holy land was: to unite the catholic church, increase papal authority, reunite the western and eastern churches and put surplus knights to work.
             It is arguable that crusading diminished, rather than increased, the economic and cultural exchange between Western Europe and the Islamic world that might otherwise have taken place. For Byzantium, the impact of the crusading movement was disastrous. The crusades coincided with, and to some extent caused a decisive shift in the balance of economic and military power between Western Europe and the Faltering Byzantine empire. Trade between Islam and the West continued despite periodic interruptions caused by crusader attacks on Syria, Egypt, and North Africa. Even though countless numbers of people died during the Christian Crusades, there were many positive effects for both the East and the West. After the Crusades halted, various trade routes opened up between Eastern and Western cities. Also, the Muslims developed new military strategies and techniques during the fights with the Europeans, and they united themselves against one cause, producing a stronger religious nation.
             These trade routes generated beneficial contact between the cultures of East and West. From the Muslims, these merchants bought spices, sugar, cloth, and cotton. Other merchants from Sicily and Aragorn traded for Tunisian gold, and Algerian wool and animal skins. Popular goods traded from the Middle East were sugar, melons, cotton, ultramarine dye, and damask cloth. Though most of the traded goods came from the Middle East, the combined efforts from both East and West bro...