Whatever its precise origins, slavery generally meant ownership by a master, the possibility of being sold, working without pay, and the status of an “outsider” at the bottom of the social hierarchy. For most, it was a kind of “social death,”7 for slaves usually lacked any rights or independent personal identity recognized by the larger society. By the time Hammurabi’s law code casually referred to Mesopotamian slavery (around 1750 B.C.E.), it was already a long-established tradition in the region and in all the First Civilizations. Likewise, virtually all subsequent civilizations—in the Americas, Africa, and Eurasia—practiced some form of slavery.

Slave systems throughout history have varied considerably. In some times and places, such as ancient Greece and Rome, a fair number of slaves might be emancipated in their own lifetimes, through the generosity or religious convictions of their owners, or to avoid caring for them in old age, or by allowing slaves to purchase their freedom with their own funds. In some societies, the children of slaves inherited the status of their parents, while in others, such as the Aztec Empire, they were considered free people. Slaves likewise varied considerably in the labor they were required to do, with some working for the state in high positions, others performing domestic duties in their owner’s household, and still others toiling in fields or mines in large work gangs.

The second-wave civilizations of Eurasia differed considerably in the prominence and extent of slavery in their societies. In China, it was a minor element, amounting to perhaps 1 percent of the population. Convicted criminals and their families, confiscated by the government and sometimes sold to wealthy private individuals, were among the earliest slaves in Han dynasty China. In desperate circumstances, impoverished or indebted peasants might sell their children into slavery. In southern China, teenage boys of poor families could be purchased by the wealthy, for whom they served as status symbols. Chinese slavery, however, was never very widespread and did not become a major source of labor for agriculture or manufacturing.

In India as well, people could fall into slavery as criminals, debtors, or prisoners of war and served their masters largely in domestic settings, but religious writings and secular law offered, at least in theory, some protection for slaves. Owners were required to provide adequately for their slaves and were forbidden to abandon them in old age. According to one ancient text, “A man may go short himself or stint his wife and children, but never his slave who does his dirty work for him.”8 Slaves in India could inherit and own property and earn money in their spare time. A master who raped a slave woman was required to set her free and pay compensation. The law encouraged owners to free their slaves and allowed slaves to buy their freedom. All of this suggests that Indian slavery was more restrained than that of other ancient civilizations. Nor did Indian civilization depend economically on slavery, for most work was performed by lower-caste, though free, men and women.