Slaves could be found in simpler societies, but more important and better known was the existence of slavery in most advanced states. This chapter discusses the spectrum of different types and levels of slave use. It focuses on slavery in pre-state societies and the correlation between slavery and cities, trade, and empires. Historians often distinguish between slave societies and societies with slaves. New World slavery was agricultural and can seem atavistic and primitive in comparison with contemporaneous industrialization with its wage laborers and technology. The growth of state power, like the growth of cities, typically went hand in hand with the increasing inequalities both of wealth and power that produced an elite who might desire slaves for their lifestyle, status, or profit. The racism directed against black Africans in New World slave systems was a modern, relatively systematic, and extreme example of a much more common attitude toward slaves.