A complex society is a concept that is shared by a range of disciplines including anthropology, archaeology, history and sociology to describe a stage of social formation. The concept was formulated by scholars attempting to understand how modern states emerged, specifically the transition from small kin-based societies to large hierarchically structured societies. A complex society is characterized by features such as: State with a large population wherein its economy is structured according to specialization and a division of labor. These economic features spawn a bureaucratic class and institutionalize inequality. Archaeologically, features such as big architectural projects and prescribed burial rites. Large scale agricultural development, which allows members of society time for specialized skill sets. Organized political structure. The term is mostly used as shorthand to indicate a society with intricate political organization and using technology to expand economic production. Before human beings developed complex societies, they lived in primitive societies. The historical consensus is that complex societies emerged from primitive societies around 4000-2000 BCE in Egypt, Mesopotamia, the Indus Valley and China. According to traditional theories of how states emerged, the initial spark for the development of complex societies was an agricultural surplus. This economic specialization leads to divisions of labor. The economic transition from an agricultural economy to a division of labor is the most basic explanation of how societies go from primitive to complex. Before the rise of complex societies, there was little need for a strong, centralized state government. The increase in populations in these societies meant that the society was too big to rely on interpersonal and informal connections to resolve disputes. This meant there was a need for a hierarchical authority to be acknowledged as the final arbiter in such scenarios. This judicial authority was also able to claim military, economic and religious authority.