A tribal chief is the leader of a tribal society or chiefdom. Tribal societies with social stratification under a single (or dual) leader emerged in the Neolithic period out of earlier tribal structures with little stratification, and they remained prevalent throughout the Iron Age. In the case of indigenous tribal societies existing within larger colonial and post-colonial states, tribal chiefs may represent their tribe or ethnicity in a form of self-government. The most common types are the chairman of a council (usually of "elders") and/or a broader popular assembly in "parliamentary" cultures, the war chief (may be an alternative or additional post in war time), the hereditary chief and the politically dominant medicineman (in "theocratic" cultures). The term is usually distinct from chiefs at still lower levels, such as village headman (geographically defined) or clan chief (an essentially genealogical notion), as the notion "tribal" rather requires an ethno-cultural identity (racial, linguistic, religious etc.) as well as some political (representative, legislative, executive and/or judicial) expression. In certain situations, and especially in a colonial context, the most powerful member of either a confederation or a federation of such tribal, clan or village chiefs would be referred to as a paramount chief. This term has largely fallen out of use, however, and such personages are now often called kings.