How Did Slavery Develop?

Figure 1. Relief from the Roman period showing a shackled slave.

Slavery has been an ancient institution that likely goes back to periods of the earliest writing if not originating even before. In fact, as an institution, modern forms of slavery, such as people trafficking, still exist, despite slavery being almost universally banned in societies today. We often think of past slavery as being associated with racial beliefs; however, the origins of this institutions do not seem to be associated with race. Slavery at times has been used as a form of punishment or to deal with prisoners of war. The history of this institution has, however, evolved over the millennia.

Early Developments

Slavery probably has its origins as warfare became more established at larger scales between societies, although very likely slavery existed at some levels even before the rise of states and cities. Both Mesopotamia and Egypt likely have some of the earliest evidence of larger-scale slavery as conflict developed when societies began to compete with each other more frequently. [1]. Initially, most slaves may have been women captured from towns or villages during raids or attacks. Later, however, men became valuable as forms of labor in agriculture, while skilled workers were put to work in construction or helping with production of materials. Slavery varied based on the skills of the individuals trained or captured.

Early depictions indicate that those captured in battles were sometimes shackled. Slaves were generally owned by the state, but by the 2nd millennium BCE private individuals also owned slaves according to written sources, although private ownership likely began even earlier. [2] Slavery, in effect, was in part based on keeping people as prisoners of war. Such slaves might be released if peace was agreed upon between warring sides. In the Indus, possible slave quarters have even been found between the 3rd and 2nd millennium BCE.[3]

In the second millennium BCE, throughout the Near East the trade of slaves developed as another market. We begin to get more information on the prices of slaves, ranging from 20-90 shekels (a form of weight) of silver. This indicates slaves were expensive and probably not commonly owned except by political, religious elites, and very wealthy households.[4]

Slavery also developed as a form of punishment for individuals who defaulted on debt. As societies became monetized by the 3rd millennium BCE, slavery became a way in which individuals were punished for falling into debt. The issue of debt increasingly became a problem as individuals had to borrow to rent land and property to conduct agriculture. If a bad harvest occurred, then debt was a likely result. In effect, slavery not only reflect the social inequality that had developed to a pronounced level by the 3rd millennium BCE, but it reflects that society had developed a system that punished those who failed to maintain that system even if was not their fault they had gone into debt. People were also born into slavery, as children of slaves.

In New Kingdom Egypt, by the late second millennium BCE, slavery did develop to the point where the excesses of owners was somewhat checked. Laws became established that forbid the over-exploitation of child labor, for instance. Ancient China developed similar laws that protected slaves from over abuse. Slavery in China seems to have developed similarly to other parts in the world where warfare and debt were the leading reasons people became slaves.[5]

Slavery was practiced in ancient Greece, where most slaves appear to have been war captives. Debt bondage, similar to the Near East and elsewhere could lead to a form of slavery, but this could be a temporary status and one could buy or earn their freedom, which was also true in the ancient Near East. Sparta may have had one of the largest slave systems. While it is hard to say what was legend and what was truth, the so-called Helots were a class of slaves that may have derived from a conquered city (Helos). Subsequent slaves were then called Helots. Sparta's slaves seem to all belong to the state and were essentially a class, where the Helots formed their own families and kin groups. In Athens, slavery was often at a private level and slaves were owned by individual households. Slave revolts began to become a problem as slaves began to outnumber their masters. In effect, by allowing slaves to have their families and also perpetuating the bondage of slavery for individuals inevitably led to populations of slaves increasing and revolting against their bondage. In ancient Rome, slaves were often privately owned. Famous slave revolts include those by gladiators such as Spartacus (Figure 1).[6]

Racial Slavery

Figure 2. Black slaves being sent to Brazil.

Slavery as a form of war booty or bondage for being in debt largely continued in many societies even after ancient periods and into the Medieval period. Slavery did vary across societies, where sometimes slaves were treated as part of the family. Slaves also had high positions of power and even sometimes became the ruling class, such as the Mamluks in Egypt. The Mamluks, meaning property, were brought in as slaves in Egypt and began to serve in the army. Over time, they became influential and took the reigns of power directly.[7]

However, racial-based slavery emerged as a new strand of slavery by the early Medieval period. Initially, Arab slave traders began to raid and establish slave colonies in Africa. The slaves, or called zanj, began to originate from Sub-Saharan Africa, which took advantage of other slave trade existing within Africa. Colonies soon developed, such as Zanzibar, that began as important ports for slave traders connecting the Arab Middle East and Africa. As many of these slaves were black, slavery over time began to be associated with racial aspects. No longer were slaves racially indistinguishable from others in society based on their skin color. Slavery and being black began to be associated together during the Medieval period.[8] Slavery, nevertheless, did continue to be applied to people from a variety of ethnic backgrounds. White Europeans, for instance, were sometimes enslaved by Arab traders and others, such as Viking raiders.

Nevertheless, the beginning of associating slavery with race in Europe began near the time of the discovery of the New World. The key change was the collapse of the Silk Road as a leading trade route in the Old World and the rise of transatlantic trade. The origin of Western race-based slavery began slightly earlier in the 15th century, with the Portuguese engaging more with Africa. From the beginning, slaves were often captured by other Africans in their inter-tribal wars. However, the New World presented itself as a vast area that needed a lot of labor and this substantially pushed the slave trade to new levels. For much of the African slave trade's history, European slave traders simply traded with Africans for slaves, where the slaves were then shipped to the New World as it became a major economic and political focus. The trade of slaves to the New World became associated with high intensity agricultural labor, such as the production of coffee and sugar cane, which were two emerging products in Europe in the 15-16th centuries (Figure 2).

It was the impetus of the slave trade that motivated European explorers to expand their exploration of Africa and the New World even more. In the 16th century, the profitability of agriculture in the New World and slaves became so great that it led to Portugal to directly take control of parts of Africa, specifically in Angola. This began the period of colonization by Europe in Africa that only ended in the 20th century. However, the trade was not completely one-way, as African states and tribes began to also exact tribute from European traders for access to the slave trade and to pay shipping fees as they moved slaves from the African coast.[9] However, over time the trade became more skewed in favor of Europeans.

By the 16th and 17th centuries, the Caribbean had emerged as a major destination for British, French, and Dutch interests. Slaves began to be moved to these areas in greater numbers. As British naval power expanded in the late 17th and early 18th centuries, they soon became the largest exporters of slaves as well as the Dutch. Europeans still mostly avoided going into interior regions of Africa, mostly depending on Africans to capture or bring them slaves. The difference between the European and African systems of slavery was the European system began to associated slavery as a racial-based enterprise, given that slaves were all black, while African slavery was based on warfare and was not even seen as inheritable to the children of slaves.[10]

Modern Day Slavery

By the 19th century, and after the American Civil War, most European and Western states had banned slavery. However, it continued to persist in many parts of the world. Slavery continued to be legal in the Persian Gulf emirates into the 1960s. However, in the 20th century, slavery once again transformed. This time, it reverted back into something that was more market driven but not based as much on race, although certain ethnic groups have been subject to slavery due to the countries of origin. High wage differences between first and third world countries has led to forms of servitude that promises financial rewards but often leads to abuse and bondage. In some states in the West, Middle East, and East Asia, human trafficking has become a problem where prostitution, legalized and illegal forms, and manufacturing have led to Eastern Europeans, Central and South Americans, South Asians, and East Asians in particular being put into positions of virtual slavery. Although slavery is now universally illegally, human trafficking can be found in nearly every country.[11]


Perhaps the core common patterns of slavery through different periods is economic disparity between those who enslave and slaves. Slavery has also been an expression of power by individuals and societies seeking to subjugate other people. At times, slavery may have served as a type of punishment system, more similar to our penal systems of today. Relative to the history of slavery, race-based slavery has only occurred in limited periods and the origins of that were economic and expressions of power over vulnerable people. We don't know if slavery developed in periods where written sources were not available. Slavery could have been an expression of human desire to dominate others or it may reflect economic disparities that emerged as resources were accumulated with the rise of social inequality.


  1. For more on the origins of slavery, see: Heuman, G. J. (Ed.). (2012). The Routledge History of Slavery (1. publ. in paperback). London: Routledge.
  2. For more on the rise of private ownership and slavery, see: Chirichigno, G. (1993). Debt-slavery in Israel and the ancient Near East. Sheffield: JSOT Press.
  3. For more on the slave quarters in the Indus, see: Catchpole, B. (Ed.). (1981). The clash of cultures: aspects of culture conflict from roman times to the present day (1. publ). London: Heinemann
  4. For market prices of slaves, see: McIntosh, J. (2005). Ancient Mesopotamia: new perspectives. Santa Barbara, Calif: ABC-CLIO, pg. 168.
  5. For more on concepts of social justice and slavery, see: Irani, K. D., & Silver, M. (Eds.). (1995). Social justice in the ancient world. Westport, Conn: Greenwood Press.
  6. For more on slavery in Greece, see: Wiedemann, T. (1994). Greek and Roman slavery (Reprinted). London: Routledge.
  7. For more on the history of the Mamluks, see: Winter, M., & Levanoni, A. (Eds.). (2004). The Mamluks in Egyptian and Syrian politics and society. Leiden ; Boston, MA: Brill.
  8. For more on the history of the early Arab slave trade, see: Curtis, V. S., Stewart, S., London Middle East Institute, & British Museum (Eds.). (2009). The Rise of Islam. London ; New York : New York: I. B. Tauris in association with The London Middle East Institute at SOAS and The British Museum : Distributed in the U.S. by Palgrave Macmillan, pg. 61.
  9. For more on the history of the African slave trade, see: Worger, W. H., Clark, N. L., & Alpers, E. A. (2010). Africa and the West: A Documentary History (2nd ed). Oxford ; New York: Oxford University Press.
  10. For more on the African system of slavery and rise of the Caribbean slave trade, see: Klein, H. S., & Vinson, B. (2007). African Slavery in Latin America and the Caribbean (2nd ed). Oxford ; New York: Oxford University Press.
  11. For more on modern slavery, see: Davidson, J. (2015). Modern Slavery: The Margins of Freedom. London New York, NY: Palgrave Macmillan.