In ancient Greece, a phratry was a group containing citizens in some city-states. Their existence is known in most Ionian cities and in Athens and it is thought that they existed elsewhere as well. Almost nothing is known about the functions and responsibilities of phratries outside Attica. Within Athens, they played a prominent role in social and religious life, particularly in the major festival called the Apatouria. They played an important role in determining eligibility for Athenian citizenship and all citizens and only citizens were enrolled in phratries. Particularly in anthropology, the term is also applied to similar descent groups of multiple clans in other societies.