Ethnogenesis (from Greek ethnos ἔθνος, "group of people, nation", and genesis γένεσις, "beginning, coming into being"; plural ethnogeneses) is "the formation and development of an ethnic group." This can originate through a process of self-identification as well as come about as the result of outside identification.
Ethnogenesis can occur passively, in the accumulation of markers of group identity forged through interaction with the physical environment, cultural and religious divisions between sections of a society, migrations and other processes, for which ethnic subdivision is an unintended outcome. It can occur actively, as persons deliberately and directly 'engineer' separate identities to attempt to solve a political problem – the preservation or imposition of certain cultural values, power relations, etc. Since the late eighteenth century, such attempts have often been related to language revival or creation of a new language, in what eventually becomes a "national literature".
In the nineteenth and twentieth centuries, societies challenged by the obsolescence of those narratives which previously afforded them coherence have fallen back on ethnic or racial narratives as a means of maintaining or reaffirming their collective identity, or polis.
Ethnogenesis can be promoted to include or exclude any ethnic minority living within a certain country. In France, the integrationalist policy of the French Republic was inclusive; their laws stated all persons born or legally residing in France proper (including overseas departments and territories) were "Frenchmen". The law did not make any ethnic distinctions nor racial categories in between the "French" people. All people in France were Frenchmen and became citizens of the French Republic as far the country's law was concerned.
Language has been a critical asset for authenticating ethnic identities. The process of reviving an antique ethnic identity often poses an immediate language challenge, as obsolescent languages lack expressions for contemporary experiences. In Europe in the 1990s, examples of proponents of ethnic revivals were from Celtic fringes in Wales and nationalists in the Basque Country. Activists' attempts since the 1970s to revive the Occitan language in Southern France are a similar attempt.