Stable food supply: A complex can thrive only if its member have enough food.
Social structure: Social structure include different jobs and social levels. People at higher levels have greater status than others.
A highly developed culture: This includes things such as painting, architecture, music and literature.
A system of government: A system of government is needed to direct people’s behavior and make life orderly.
A religious system: A set of beliefs, usually in a god, together with forms of worship.
Advances in technology: They must have created practical tools and inventions.
A highly developed written language: There must be some form of written language within the civilization.