@Xeniax in james scott's "the art of not being governerned" he describes various practises of fluid identities -- people maybe lived for 10 years in a city-state and then evaded famine or conscripting and went to the hills/woods and then joined this group, then maybe another, and would even sometimes return to the city-state (after a few years) -- identify was far less fixed than what we are used to in the current "national-state-with-strict-boundaries" worlds.