THIRTY YEARS AGO this month, the collapse of the Shah's government marked the launch of Iran's Islamic Revolution, and since that point the topic of Islam has rarely been out of the headlines. All too often, we hear about Islam in the context of intolerance and, often, violence -- of Al Qaeda savagery, of Taliban misogyny, of nuclear weapons in Pakistan and perhaps in Iran itself. Even in Europe, many fear the growth of a radical Islamic presence. For three decades, Western observers have worked fervently to comprehend Islam's global power and appeal, its ability to inspire the poor and to topple governments. But in all that intense attention, most observers have missed a crucial part of the story: a global web of devout religious brotherhoods that by all logic should be a critical ally against extremism. Sufis are the power that has made Islam the world's second-largest religion, with perhaps 1.2 billion adherents. Not a sect of Islam, but rather heirs of an ancient mystical tradition within both the Sunni and Shia branches of the faith, Sufis have through the centuries combined their inward quest with the defense and expansion of Islam worldwide. At once mystics and elite soldiers, dervishes and preachers, charismatic wonder-workers and power-brokers, ascetic Sufis have always been in the vanguard of Islam. While pushing forward the physical borders of Islam, they have been essential to the spiritual and cultural fullness of the faith. Today, the Sufi tradition is deeply threaded through the power structures of many Muslim countries, and the orders are enjoying a worldwide renaissance. To look at Islam without seeing the Sufis is to miss the heart of the matter. Without taking account of the Sufis, we cannot understand the origins of most contemporary political currents in the Middle East and Muslim South Asia, and of many influential political parties. We can't comprehend the huge popular appeal of Islam for women, who so often seem excluded from Muslim life. Sufis are central to the ability of Muslim communities to survive savage persecutions -- in Chechnya, in Kosovo -- and then launch devastating insurgencies. They are the muscle and sinew of the faith. And, however startling this may seem, these very Sufis -- these dedicated defenders and evangelists of mystical Islam -- are potentially vital allies for the nations of the West. Many observers see a stark confrontation between the West and Islam, a global conflict that entered a traumatic new phase with the Iranian revolution. But that perspective ignores basic conflicts within the Muslim world itself, a global clash of values over the nature of religious practice, no less than overtly political issues. For the Islamists -- for hard-line fundamentalists like the Saudi Wahhabis and the Taliban -- the Sufis are deadly enemies, who draw on practices alien to the Quran. Where Islamists rise to power, Sufis are persecuted or driven underground; but where Sufis remain in the ascendant, it is the radical Islamist groups who must fight to survive.

Around the world, the Sufis are struggling against violent fundamentalists who are at once their deadly foes, and ours. To look at Islam without seeing the Sufis is to be ignorant of a crucial clash of civilizations in today's world: not the conflict between Islam and the West, but an epochal struggle within Islam itself. If the word "Sufi" conjures up any images for Americans, they normally involve mystical poetry or dance. Thirteenth century poet Rumi was a legendary Sufi, as are Turkey's whirling dervishes. But these are just the most visible expressions of a movement that runs deeply through the last thousand years of Islam. Emerging around the year 800, they were originally pious devotees, whose poor woolen clothes showed their humility: "Sufi" comes from the Arabic word for wool. Above all, the Sufis sought the divine reality or ultimate truth that stands above all the illusions and deceptions of the material world. In order to achieve ecstatic union with God, they incorporated techniques of sound and movement -- chanting and music, swaying and dance. Believers joined in tight-knit brotherhoods or tariqahs, each following a charismatic leader (shaykh). Among the dozens of these orders, a few grew to achieve special influence, and some operate in dozens of nations, including the United States. But the orders are more than confraternities of pious devotees. Early in their history, Sufis developed a powerful military streak, making them the knights of Islam, as well as the monks and mystics. Like the Japanese samurai, the brotherhoods trained their followers to amazing feats of devotion and overcoming pain. Fanatical dervish warriors were the special forces of every Islamic army from the 13th century through the end of the 19th. The expansion of Islam outside the core areas of the Middle East is above all a Sufi story. Sufi orders led the armies that conquered lands in Central and South Asia, and in Southeastern Europe; through their piety and their mysticism, the brotherhoods then won the local populations over to Islam. They presented an Islam that incorporated local traditions and worship styles, including Christian saints and Hindu gods. Today, Sufi styles and practices dominate in the non-Arab Muslim world: in India and Pakistan, in Indonesia and Malaysia, Nigeria and Senegal, and in the Muslim countries of Central Asia, such as Uzbekistan and Tajikistan. Over the centuries, the territories where Sufi orders seeded Islam have evolved from the faith's frontiers to its demographic heartlands. These regions now encompass Islam's largest and fastest-growing populations. Of the eight nations with the world's largest Muslim communities, only one (Egypt) is Arab. A fifth of the world's Muslims today identify with Sufism, and for many millions more, Sufism is simply part of the air they breathe.

The Sufi orders enhanced their political role as Western empires encroached. When Islam was under threat, the Sufis were the trained soldiers, and their close-knit brotherhoods allowed them to form devastatingly effective resistance movements. Sufi orders led anti-colonial movements from Morocco to Indonesia. Most Americans, for instance, have heard of the stubborn Chechen guerrillas, but few realize how absolutely this movement is rooted in Sufism. When the Russians pushed south into Muslim lands in the 19th century, the heroic Sufi sheikh Imam Shamil launched a decades-long guerrilla war. Even Stalin's terror campaigns could not root out the Sufi brotherhoods. The fearsome leader of modern-day Chechen resistance, Shamil Basayev, was named for the original imam. A similar story can be told of other oppressed peoples, in Kurdistan, Kashmir, Albania, Kosovo, and elsewhere, who owed their solidarity and cohesion to the immense power of the Sufi brotherhoods. The Sufis might sound like America's worst nightmare. Not only do they ground political activism in religion, but their faith spreads through intense and secretive brotherhoods, led by charismatic masters: this recalls every sinister stereotype of Muslim fanaticism that potboiler thrillers have offered us over the decades. But it would be a terrible mistake to see the Sufis as enemies. Sufis certainly have fought Western forces through the years, and Sufi-founded movements have on occasion engaged in terrorist actions -- witness the Chechens. But in the vast majority of cases, such militancy has been essentially defensive, resisting brutal colonial occupations. This is very different from the aggressive global confrontation pursued by groups such as Al Qaeda. Today, moreover, Sufi brotherhoods face a deadly danger from the strict puritanical or fundamentalist Islam represented by Qaeda and similar movements, which are as threatening to the Sufi brotherhoods as they are to the West. To the extent that we, like the Sufis, face a real danger from violent jihadi fundamentalism, our interests are closely aligned with those of the Sufis. But the Sufis are much more than tactical allies for the West: they are, potentially, the greatest hope for pluralism and democracy within Muslim nations. The Sufi religious outlook has little of the uncompromising intolerance that characterizes the fundamentalists. They have no fear of music, poetry, and other artistic forms -- these are central to their sense of the faith's beauty -- and the brotherhoods cherish intellectual exploration. Progressive Sufi thinkers are quite open to modern knowledge and science. From their beginnings, too, Sufi traditions have been religiously inclusive. Wherever the orders flourish, popular Islamic religion focuses on the tombs of saints and sheikhs, who believers venerate with song and ritual dance. In fact, they behave much like traditional-minded Catholics do when they visit their own shrines in Mexico or southern Italy. People organize processions, they seek healing miracles, and women are welcome among the crowds. While proudly Islamic, Sufi believers have always been in dialogue with other great religions.