''Luaitear na historicalfianna institutiongo ofstairiúil the ''fiann'' is known from references insan [[Brehonan LawsFéineachas|Fhéineachas]]. AMar bhaill d''fiann''fhiann wasbhíodh madefir upagus ofmná landlessóga gan talamh young men and women, oftengo youngminic [[Aristocracyuaslathaithe (class)|aristocrat]]snach whobhfuaireadar had not yet come into their [[inheritance]]fós ofa landn-oidhreacht.<ref>Dáibhí Ó Cróinín, ''Early Medieval Ireland'', Longman, 1995, lch. 88</ref> ''Féinní'' (''fénnid'') a glaodh ar ball d'fhiann; ''ríféinní'' (''rígfénnid'') ab ea ceannaire féinne.
'' [[Seathrún Céitinn]], in his 17th-century ''[[Foras Feasa ar Éirinn]]'', says that during the winter the Fianna were quartered and fed by the nobility, during which time they would keep order on their behalf, but during the summer, fromó [[Bealtaine|Bhealtaine]] togo [[Samhain]], they were obliged to live by hunting for food and for pelts to sell.<ref>[[Seathrún Céitinn]], ''[[Foras Feasa ar Éirinn]]'', [http://www.ucc.ie/celt/published/T100054/text055.html 2.45]</ref> Keating's ''History'' is more a compilation of traditions than a reliable history, but in this case scholars point to references in early Irish poetry and the existence of a closed hunting season for deer and wild boar between'' idir Samhain andagus Bealtaine in medieval [[Alba]] asmeánaoiseach mar corroborationchomhthacaíocht.<ref>Nerys Patterson, ''Cattle Lords and Clansmen: the Social Structure of Early Ireland'', University of Notre Dame Press, 1994, lch. 122-123</ref>
