In anthropology and archaeology, a complex society is a social formation that is described as a formative or developed state. The main parts of complexity are:

• the extent of a division of labour in which members of society are more or less permanently specialized in particular activities and depend on others for goods and services, within a system regulated by custom and laws.
• the population size of a human community; the larger the population, the more complex and variegated the co-existence of people tends to become.