The Unknown Slavery: In the Muslim world, that is -- and it's not over.

When Henry Morton Stanley explored the Congo River's Boyoma Falls, the cascades weren't the only thing he noticed: "Every three or four miles we came in view of the black traces of the destroyers. The scarred stakes, poles of once populous settlements, scorched banana groves, and prostrate palms, all betokened ruthless ruin."

The perpetrators of this wreckage were slavers. As late as 1883 -- when Stanley wrote -- they were scouring the African countryside for people they could seize and haul into bondage. Their gruesome search destroyed whole villages, leaving once-prosperous areas devoid of inhabitants. Their forced marches to the coast were ghastly, with the exposed bones of captives who died along the way so numerous they practically served as trail markers. Those who survived the ordeal -- fewer than half, by some estimates -- were exported to the world's final repository of slavery: the Islamic world.

The phenomenon of Muslim slavery is not often studied, and especially not the Muslim enslavement of black Africans. "A list of serious scholarly monographs on [Islamic] slavery -- in law, in doctrine, or in practice -- could be printed on a single page," wrote Princeton's Bernard Lewis in his pioneering but brief book Race and Slavery in the Middle East (1990). He went on to suggest that the subject is so "highly sensitive" that it would be "professionally hazardous" for young scholars to take it up. Indeed, among the thousands of professors and graduate students affiliated with Middle Eastern studies programs in the U.S., only a handful have dared to broach the controversial topic, and a comprehensive history and analysis of it remains to be written.

This stands in stark contrast to the huge amount of scholarship on slavery in the West. Judging by the sheer volume of material, one might come away with the mistaken impression that nowhere was the vile institution of slavery more entrenched than among the American hypocrites who declared that all men are created equal. And yet throughout Muslim history, starting with Mohammed himself, slavery was a vigorous and central part of Islamic civilization. This is not to say Islamic slavery was worse than American slavery; in many ways, life was easier under Muslim owners than under Mississippi owners. The problem, rather, is that the Islamic world has not experienced the same kind of moral reckoning on slavery that the West has. Muslim countries proved extremely resistant to abolition; many of them had to be dragged into it by the European colonial powers. It is hard to imagine a serious person calling for America to enslave its enemies. Yet a prominent Saudi cleric, Shaikh Saad Al-Buraik, recently urged Palestinians to do exactly that with Jews: "Their women are yours to take, legitimately. God made them yours. Why don't you enslave their women?"

Words are one thing, and actions another. Even today, however, Islamic abolition cannot be called a complete success: Slavery continues to be practiced in at least two nations whose regimes claim to derive their legitimacy from Islam. These nations are Mauritania and Sudan, and Muslims remain virtually silent about the practices of their coreligionists there.

Slavery is an ancient institution, as old as recorded history. Aristotle defended it; both the Old and New Testaments accept it as a feature of the human condition. The Koran takes a similar view -- though it also encourages (without commanding) slaveholders to treat their slaves well, and urges (without requiring) their release. In Islamic theology, slave ownership is a morally neutral act, but God smiles on those who give slaves their liberty.

The characteristics of Muslim slavery have been far from uniform over the centuries, but it is possible to identify a few general traits. For starters, slaves were accorded more legal protections in the Islamic world than they received almost anywhere else. Slavery came under an intricate set of regulations that, for example, forbade the use of slaves as prostitutes, and prevented mothers and young children from being separated. The act of enslavement also wasn't supposed to occur on Muslim soil, though the slavers and their customers didn't always pay close attention to this rule. In the 19th century, Captain G. F. Lyon of the Royal Navy described slaveholding in Libya: "They seize on the inhabitants of whole towns where the only religion is that of the Koran, and where there are mosques; and this is without scruple or remorse."

There was plenty of cruelty -- slavery, of course, always involves cruelty -- but many chattels of Muslims were essentially domestic workers who functioned as surrogate members of the master's family. "Slaves in Islam were directed mainly at the service sector -- concubines and cooks, porters and soldiers -- with slavery itself primarily a form of consumption rather than a factor of production," writes Ronald Segal in Islam's Black Slaves. Perhaps the most important difference between slavery in the West and slavery in Islam is a demographic one: Two-thirds of the slaves transported across the Atlantic were male, and two-thirds of those involved in the Muslim trade were female.

Over time, sub-Saharan Africa became the principal source of involuntary labor. Muslims were not the first people to enslave black Africans -- the ancient Egyptians had done it -- but they were the first to engage in it systematically on a massive scale. Going back to Islam's birth in the 7th century, historian Raymond Mauvy estimates that 14 million black slaves have been sold to Muslims. (This compares to Paul E. Lovejoy's estimate of 10 to 11 million Africans shipped in chains to the Western Hemisphere between 1650 and 1900; the vast majority of them were sent to Latin America and the Caribbean, and half a million to British North America and the U.S.) The journey from the slave's homeland to the Middle East was often a treacherous one, especially when it involved enduring the blistering heat of a Sahara crossing. Yet the march was dangerous everywhere -- an Islamic version of the brutal Middle Passage. The dead frequently outnumbered the survivors on these journeys, often by a lot. Slavers accepted the high casualty rates because their business was so lucrative. "It is like sending up to London for a large block of ice in the summer," wrote a 19th-century missionary in what is now Tanzania. "You know that a certain amount of it will melt away before it reaches you . . . but that which remains will be quite sufficient for your wants."

The oddest aspect of Islamic slavery was the eunuch. Castrated male slaves became exceedingly popular in the Middle East sometime after the rise of Islam. They are best known for serving as harem guards, but they were also mosque custodians, administrators, and teachers. Eunuchs were bought and sold at a premium, in part because their grisly operation resulted in many fatalities. Their popularity remains something of a mystery. "One can only speculate that eunuchs were regarded as likely to be more devoted and dependable in serving their masters than other males, with normal distractions, would be," writes Segal. Whatever the reason, eunuchs became fixtures of Muslim culture. Islam teaches against physical mutilation, so Muslims found themselves searching for loopholes. Many eunuchs were castrated in non-Muslim territory immediately before importation, in the belief that this somehow kept Islamic land pure; a business in commercial castration thus developed along the fringes of the Muslim world. (Prague is said to have specialized in this during the period when Islam imported many slaves from Europe.) Muslims later accepted castration within their own lands, so long as non-Muslims performed the deed.

Slavery, in short, was an ingrained part of Islamic culture -- and it might still have been one today, but for European insistence that Muslims end it. As recently as 1878, the holy cities of Mecca and Medina served as major slave markets, trading 25,000 slaves annually. The eradication of slavery, in fact, is one of the great and unheralded legacies of colonialism.

The first Islamic countries to abolish slavery -- Tunisia, Egypt, the Ottoman Empire -- did so under pressure from the West. Others were more obstinate. In East Africa, slavery continued until after World War I. Its persistence into the 20th century explains why the League of Nations prioritized the abolition of slavery, even though doing so must have seemed an anachronism to unsuspecting Westerners. It wasn't until the start of World War II that Ethiopia and Liberia had gotten rid of slavery. Later still, the U.N.'s Declaration of Human Rights condemned slavery -- again, because the Islamic world had failed to wipe it out. In 1953, sheikhs from Qatar attending the coronation of Queen Elizabeth II included slaves in their retinues, and they did so again on another visit five years later. Saudi Arabia and Yemen didn't get around to abolishing slavery until 1962; three years later, a special report by the U.N. reported that the Saudi royal family continued to keep hundreds in bondage.

Mauritania outlawed slavery in 1980, apparently because its two earlier prohibitions (in 1905 and 1960) were ignored. Today, it is illegal for Mauritanians to say that slavery exists in their country -- a sure sign that it really does. By some estimates, at least 100,000 of Mauritania's 2.7 million people continue to live in unpaid servitude, most of them blacks toiling for light-skinned Moorish masters. Slavery goes back centuries in Mauritania, and there's a long tradition of slaves' working for the same family across generations. Apologists say that those who remain in this capacity aren't slaves at all, but servants who volunteer to trade their labor for room and board. Yet these claims are effectively rebutted by a small group of escapees who have delivered powerful personal testimonies of beatings and bondage. Reliable information on what's really happening in Mauritania is hard to come by because the Islamic government won't allow investigations. Foreign journalists must travel in the company of the secret police and face expulsion if they ask too many questions. In January, the government banned the main opposition party, which has demanded slavery's eradication. Mauritania has far to go before slavery ceases within its borders.

Sudan has received considerably more attention than Mauritania. In April, an organization affiliated with the Boston-based American Anti- Slavery Group made headlines by purchasing 3,000 slaves at $33 apiece and releasing them, and also negotiating the release of 3,000 others. Another group, the Swiss-based Christian Solidarity International, says it has bought freedom for 60,000 slaves in Sudan over the last several years. (This raises a separate question: Does buying slaves from modern-day slave traders wind up perpetuating their wretched business?) As with Mauritania, there are no truly credible numbers describing the extent of the problem. Sudan has engaged in slaving and slaveholding for ages; the current wave seems to have begun in 1983, with the imposition of Islamic law. Following the 1989 coup by the Islamofascist general Omar el-Bashir, the government became actively involved in arming the slavers and supporting their operations in the southern part of the country, where Muslims are outnumbered by Christians and other non-Muslims. These slavers' methods are especially vicious: The men are shot, the women and girls are sold into concubinage, and the boys are fortunate if they become unpaid cattle herders.

In considering the history of slavery in Islam and in the West, it is a mistake to decide that one branch of the same evil represents the greater sin. Instead, it is probably enough to say the human toll in both places was horrible: Call it "immoral equivalence." But there's an important difference today. The United States finds itself apologizing for slavery (at least when Bill Clinton visits Africa), handing out huge amounts of foreign aid (partly from a sense of guilt), and giving at least passing thought to financial reparations for the descendants of its own slaves. Yet when Muslim countries gather at international forums, they discuss none of this -- and instead spend their time writing resolutions bashing Israel and the West. They appear to feel no remorse for the past, and no responsibility for the present. While the West has its problems, it does not have this one.