An association of neighboring states or tribes in ancient Greece; established originally to defend a common religious center WordNet 3.0 & Open English WordNet

In Archaic Greece, an amphictyony, or amphictyonic league, was an ancient religious association of tribes formed before the rise of the Greek poleis. Wikipedia

Pre-polis type of ancient Greek confederacy Wikidata

A religious foundation or co-operative shared between Greek city states during the classical period, typically to support the temple or cult of a deity shared by the city states. Also used academically to refer to similar arrangements in non-Greek cultures. Wiktionary

Religious cooperation among ancient Greek city-states. Wiktionary (translation)