Evidence of slavery predates written records, and has existed in many cultures.[3] Prehistoric
graves from about 8000 BC in Lower Egypt suggest that a Libyan people enslaved a
San[disambiguation
needed ]-like tribe.[16]
Slavery is rare among hunter–gatherer populations, as slavery
is a system of social stratification. Mass slavery also requires economic
surpluses and a high population density to be viable. Due to these factors, the
practice of slavery would have only proliferated after the invention of
agriculture during the Neolithic Revolution about 11,000 years
ago.[17]
The earliest records of slavery can be traced to the oldest known records,
which treat it as an established institution, not one newly instituted. The Code of Hammurabi
(ca. 1760 BC), for example, stated that death was prescribed for anyone who
helped a slave to escape, as well as for anyone who sheltered a fugitive.[18] The Bible refers to slavery as an established
institution.[3]
Slavery was known in civilizations as old as Sumer, as well as almost every other ancient
civilization, including Ancient Egypt, Ancient China, the Akkadian Empire, Assyria, Ancient India, Ancient Greece, the Roman Empire, the Islamic Caliphate, and the pre-Columbian civilizations of
the Americas.[3] Such
institutions were a mixture of debt-slavery, punishment for crime, the
enslavement of prisoners
of war, child
abandonment, and the birth of slave children to slaves.