Chiefdom
A chiefdom is a form of hierarchical political organization in non-industrial societies usually based on kinship, and in which formal leadership is monopolized by the legitimate senior members of select families or 'houses'. These elites form a political-ideological aristocracy relative to the general group. A chiefdom is thus led by a highly ranked incumbent of an inherited political role, chief: chiefs lead because of their ascribed status, not their achieved status.
Overview
In anthropological theory, one model of human social development rooted in ideas of cultural evolution describes a chiefdom as a form of social organization more complex than a tribe or a band society, and less complex than a state or a civilization. The most succinct definition of a chiefdom in anthropology is by Robert L. Carneiro: "An autonomous political unit comprising a number of villages or communities under the permanent control of a paramount chief" (Carneiro 1981: 45).
Simple
Chiefdoms are characterized by centralization of authority and pervasive inequality. At least two inherited social classes (elite and commoner) are present. (The ancient Hawaiian chiefdoms had as many as four social classes.) An individual might change social class during a lifetime by extraordinary behavior. A single lineage/family of the elite class becomes the ruling elite of the chiefdom, with the greatest influence, power, and prestige. Kinship is typically an organizing principle, while marriage, age, and sex can affect one's social status and role.