Not all Moslems were thrilled by as Islam grew from the faith of a few desert nomads to the religion of an empire. Disgusted by the worldliness of the early Umayyad Caliphs, some mystics withdrew to the desert for solitary contemplation of the divine. As with Christian mysticism, some of these pious men gained followers, and before long various "schools" of Sufism arose.

At first these mystics were noted for their attention to the "doomsday" verses of the Q'uran. As time progressed, many of the Sufi mystics became less concerned with mourning and more concerned with joy. They sought to gain direct knowledge of Allah through various mystical practices, notably dancing and singing. The Sufis also welcomed women. The Persian Sufi Abü 'Abd ar-Rahman as-Sulami wrote a history of eighty-two female Sufi Wadis (saints) who gained acclaim for their wisdom and their understanding of complex Q'uranic issues. One of the most important concepts in Sufi mysticism, "selfless love for the divine," was first expressed by Rabi'a al-'Adawiya, the most important female saint of Sufism.

Sufism spread rapidly as the Islamic Empire expanded. Those who would never be able to make the pilgrimage to far-away Mecca were able to make pilgrimages at the tombs of great Sufi leaders; the Sufis were also willing to draw from the religious teachings of others and add them into their philosophy. The Bektashi Sufis of Albania were known to celebrate both Christmas and Ramadan, while many of the Sufi ideas on the role of the Nafs (ego) as stumbling block owe a great deal to Hinduism and Buddhism. All this has led to tension between the Sufis and more "orthodox" Moslems; even today some Imans condemn Sufism as rank heresy, while others praise Sufi devotion to and love of Allah.

Sufi brotherhoods have played an instrumental role in the history of the Caucasus Mountains. In the seventeenth and eighteenth centuries the Naqshbandiya brotherhoods organized the struggle against the Buddhist Kalmyk invaders; later, they would provide the backbone for two centuries of resistance against the Russians. In 1944 Stalin deported the Chechens and Ingush en masse to work camps in Siberia and Kazakhstan. In those camps a new Sufi order arose, the Vis Haji. Militantly orthodox and militantly anti-Western, the Vis Haji would later be influenced by Wahhabi Islam through Saudi-funded missionaries and through Muhajjadeen who traveled to Chechnya for jihad. Today the Vis Haji continue to lead the fight against Russians in Chechnya, and a large number of Chechens were numbered among Bin Laden's Al-Qaeda troops.