Why did the First Crusade prevail?

"Most Crusades historians now believe that the First Crusade prevailed because the Arab world was already disintegrating by the late 11th century. In the first three centuries after Muhammad's death, Islamic and Arab civilization were synonymous. The Arabs dominated an area that encompassed most of Asia Minor, North Africa, Spain, and Southern Europe. Aside from the Byzantines, they maintained the most highly developed civilization in Europe and western Asia at that time. This is not the complete story, however.

Christian monastic presence and influence in the pre-crusade Muslim world

Since the earliest days of Islam, christian monasticism was a protected institution of a protected religious minority. This protected status of Christianity and monasticism in early Islamic society is emphasized by the important roles some Christians played under islamic rule.