Think slavery ended centuries ago? Think again. As you read this, upwards of 40 million human beings are being held against their will and forced to work. Modern-day slaves may be bought and sold for as little as $40, despite universal illegality. 

Slavery Slavery

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    People who enslave others make huge profits, contributing to a global black market value of some $150 billion per year, all this on the backs of the greatest number of enslaved people at any time in human history. Today, in the 21st century, humankind has still not put an end to what is regarded as one of the greatest evils that have accompanied (some would say enabled) the rise of complex civilizations.

    Slavery: Definition

    The slavery you no doubt learned about in school was probably the chattel slavery of the Trans-Atlantic Slave Trade, in which 12.5 million human beings were bought and sold as commodities. As shocking and pervasive as this practice was (and is), it is just one of four or five distinct categories of slavery we will look at.

    Slavery: The widest definition of this term is the involuntary servitude of human beings. A narrower definition excludes certain categories such as penal servitude or is limited to conditions of forced labor without pay.

    Types of Slavery

    Chattel Slavery: People are the property of other people. Enslaved people are typically captured in battles, raids, or kidnappings. Others are born into slavery. Once captured, slaves are trafficked to buyers. They may not ever have any options other than escape to gain freedom.

    Bonded Labor: Debtors provide themselves or others (often, their children) to creditors in repayment of a debt. The debt may be financial or some sort of social or religious obligation such as a bride's dowry or service to a temple. Servitude may be only a few months or it may stretch for years and sometimes in perpetuity if the debt cannot be paid off. It is the most common type of slavery today, entailing agricultural labor, industrial labor, prostitution, domestic servitude (maids), and many more categories.

    Forced Labor: Serfs, child soldiers, military conscripts, and prisoners are some of the most prominent types of enslaved people in this category.

    Forced labor does not entail ownership by someone, and there are often "ways out" of the condition, even if one was born into it (e.g., serfdom). For prisoners, this is serving of the sentence; for conscripts, once their military service is complete; for serfs and agricultural peons in general, emigration.

    Some forced labor is remunerated, though typically at low rates. People forced to work for others or the state may have some rights but are denied others.

    Slavery end child slavery protestors StudySmarterFig. 1 - Protestors wearing "Abolish Child Slavery" banners in English and Yiddish at a 1909 labor parade in New York City

    Child Slavery: As minors, children do not have the full rights and responsibilities of adults. In agricultural societies, they may be expected to perform physical labor without remuneration or choice at a young age, thus the line between tradition and exploitation can be difficult to draw. It is crystal clear, however, when children are forced to work in factories, are sold into the sex trade, are sent into the streets to beg, or are conscripted as child soldiers (the case of some 300,000 children in the world today).

    Forced Marriage: Some measures of slavery include this category. It is still common and expected in many countries across the world for marriage to take place by abduction: the groom simply steals the bride as he would a captive in battle. In South Asia, prospective brides often have no say in whom they are married to or at what age, as marriages are contracts between families and husbands.

    History of Slavery

    Slavery has existed for at least 5,000 years and on all inhabited continents; it is recorded as early as Sumer in the Fertile Crescent. It appears to have evolved with social stratification, associated with the dominance of agriculture and the formation of an elite, urban-based ruling class. Slavery arose independently in the Old World and the New World, probably numerous times. Thus, slavery did not diffuse as a cultural practice from any single place. You name the empire or kingdom in any era or region: nine (or ten) times out of ten, it allowed and even promoted slavery.

    Slavery has involved systems of institutionalized racism and other culture-based discriminatory practices as justifications for political systems that enable the practice, but it is underpinned by the profit motive.

    Many egalitarian societies have rejected the very notion of slavery. These include societies without social stratification, the norm before the dominance of agriculture. People who hunt, gather, and fish and live in small, interdependent bands (the only type of society that existed until a few thousand years ago) typically do not and have never practiced any form of involuntary labor.

    Christian, Muslims, and Slavery on a Global Scale

    Two universalizing religions, Christianity and Islam, took slavery to a new level by making slaves an underpinning of their economies. They even justified slavery by quoting scripture. Slavery of non-Muslims by Muslims began in the 600s and continued into the 20th century, involving millions of enslaved people. Meanwhile, the entire Christian world derived vast political reach and massive economic power from the Trans-Atlantic Slave Trade (1500s-1800s); the last Western country to ban chattel slavery was Brazil, in 1888.

    In the Muslim World, slavery was a continuation of pre-Islamic practices in many places. Source areas were south of the Sahara (the Trans-Saharan Slave Trade and Indian Ocean Slave Trade) and to a lesser extent across Europe and Asia. The Ottoman Empire continued the practice into the early 20th century.

    Slavery Yemen market StudySmarterFig. 2 - Slave market in Yemen, 1200s AD

    Slavery in Africa

    In the Christian World, the focus was on buying slaves from African intermediaries. Africa, like all continents, had many types of slavery before Christians and Muslims arrived. As you might guess, the most highly stratified societies tended to rely the most upon slaves. Some societies in the interior of the continent were beset by slave raiders over centuries from networks supplying the Muslim World and the Christian World at the same time! African elites in societies such as the Ashanti derived huge financial benefits from the Trans-Atlantic Slave Trade.

    Slavery in the Americas

    In the New World, stratified societies such as the Inca and many in Mesoamerica practiced different types of slavery before European contact. Most of these stratified societies collapsed quickly from Old World diseases and conquest, and the Sublimus dei papal bull of 1537 officially outlawed the slavery of Indigenous people, declaring them human beings with souls. This was taken somewhat seriously in Spanish and Portuguese society. However, various systems of forced labor of Indigenous people continued: the encomienda system and repartimiento formed the backbone of serfdom that in many ways continues today in parts of Latin America, though in a different guise.

    Christianity's Justifications for Slavery

    The Trans-Atlantic Trade grew as the labor pool of Indigenous people shrank and religious prohibitions came into effect. Christianity was able to justify the enslavement of Black Africans by claiming that enslaved people were "pagans" or Muslims and thus they were better off becoming Christians. Slavery would bring Africans the benefits of white civilization, it was preached. Other arguments cast enslaved people as "children" or as less intelligent than whites. As millions crossed the ocean in chains to supply the exploitative and increasingly lucrative plantation economy of cotton, sugar, and other crops, conditions became increasingly harsh, particularly following slave revolts in the US and across Latin America, and after 1804, the independence of Haiti.

    British Slave Trade in Indigenous People

    The British had few qualms about enslaving anyone who was not white. In a notorious example, the Indian slave trade in the Southeastern US between 1670 and 1720 involved the trafficking of tens of thousands of Indigenous people. The Chickasaw, a powerful nation based in the Mississippi Valley, raided widely for slaves to trade to the British in the Charleston market. These slaves, from ethnic groups that were in some cases driven to extinction by the practice, ended up primarily in New England and the Caribbean.

    French and Haiti

    For the French, slavery was a scientific enterprise. Sugar plantations were the most advanced production model of their time, engineered to be highly efficient forms of global capitalism. Despite freedom, liberty, and equality being promoted in the 1780s French Revolution, the racism inherent in slavery continued apace. Slavery was banned in 1794 but brought back in 1802 under Napoleon. In Haiti, one of France's most productive colonies, slave revolts in the late 18th century led to independence in 1804: the second country in the New World, after the US, to gain its freedom from Europe.

    End of Slavery

    We would love to be able to assure you that slavery ended in the British Empire with the Slavery Abolition Act 1833, or in the US with Lincoln's 1863 Emancipation Proclamation, or in 1888 in Brazil, or in even in Mauritania in 1981, the last country to ban slavery. But we can't.

    As we mentioned at the outset, slavery, while illegal everywhere, is still alive and well, with more slaves than ever. It is little consolation to the world's 40 million enslaved people to learn that entire economies no longer depend on legal slavery. By the standards of a presumably more enlightened future, the current reality of millions of children toiling away as slaves in sweatshops to produce goods for Western consumers will seem as barbaric as chattel slavery pre-1863 in the US does to us now.

    Slavery modern slavery map StudySmarterFig. 3 - Even the countries with the lightest colors have significant numbers of slaves

    To put this in stark relief: the US has an estimated 400,000 slaves today even if we exclude the forced labor for nothing or pennies in the penal system. These include bonded agricultural laborers, other categories of bonded undocumented immigrants, sex slaves, and many more.

    Even chattel slavery still exists, most notoriously in Mauritania, which has banned the practice several times, but to little avail. The collapse of Libya after a 2011 NATO bombing campaign led to documented reports of open-air slave markets being resuscitated there, part of the broader trans-Saharan migrant trade.2 Meanwhile, terrorist groups such as Boko Haram and ISIS have openly practiced slavery, while the Janjaweed militias that plague Darfur in Sudan have also been accused of practicing slave raids.

    Modern Slavery by the Numbers

    Overall, 50% of all contemporary enslaved people are involved in forced labor, with trafficking in everything from sex to nail salons dominant. Children comprise 1/4 of all slaves today; 70% of slaves are women. The worldwide industry of $150 billion is second only to drug trafficking among illicit economic categories. Enslaved people average $340 in price, ranging from the thousands of dollars for sex slaves to as little as $40 as bonded laborers in certain African countries. Extremely low prices of people are one of the main incentives for modern slavery; compare this to around $40,000 for an enslaved person bought at auction in 1809 in the US South (adjusted to 2022 US dollars).

    Penal Labor

    The world's two largest economies, the US and China, both have vast systems of penal labor remunerated slightly or not at all. In China, the infamous laogai system of forced prison labor is now highly secretive, after allegations that "reform" essentially constitutes slavery. The situation in the US is more open: for-profit companies operate prisons and are allowed to pay prisoners far below minimum wage; in a few states, prisoners are forced to work and are not remunerated.

    Slavery - Key takeaways

    • Slavery is involuntary servitude and has existed for 5,000 years at least and in most human societies.
    • The Christian and Muslim worlds benefited from institutionalized chattel slavery for centuries, particularly of people from sub-Saharan Africa.
    • Some 40 million human beings are currently enslaved, 1/4 of them children.


    1. Fig. 3 Modern slavery map ( by Homunculus 4 licensed by CC BY-SA 4.0 (
    2. Graham-Harrison, E. "Migrants from west Africa being ‘sold in Libyan slave markets’." The Guardian, April 10, 2017.
    Frequently Asked Questions about Slavery

    What are the 3 types of slavery? 

    Chattel slavery, Forced labor, and bonded labor are three most commonly listed types of slavery. 

    Who founded slavery? 

    No one founded slavery - it has been a human institution for at least 5,000 years. 

    What did slavery mean? 

    Slavery always meant involuntary servitude: you are forced to work against your will, and may be the property of someone else. 

    Who started slavery and when did it start? 

    Slavery began with the first stratified societies such as those in the Fertile Crescent (like Sumer) 5,000 years ago, when labor was needed in agriculture. 

    Does slavery still exist?  

    Yes, 40 million are currently enslaved, the most at any time in human history. Slavery is illegal everywhere, but is part of a $150 billion/year trade. 

    Test your knowledge with multiple choice flashcards

    How many enslaved people are there in the world at present?

    Which of the following factors contribute to the existence of slavery?

    What percentage of modern-day slaves are children?


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