Anthropologist Elman Service distinguishes two stages of tribal societies: simple societies organized by limited instances of social rank and prestige, and more stratified societies led by chieftains or tribal kings (chiefdoms). Historically, tribal societies represent an intermediate stage between the band society of the Paleolithic stage and civilization with centralized, super-regional government based in cities. Stratified tribal societies led by tribal kings thus flourished from the Neolithic stage into the Iron Age, albeit in competition with urban civilisations and empires beginning in the Bronze Age.