The Irish people (Irish: Muintir na hÉireann héireann Or hÉireannaigh) heireannaigh héireannaigh are a nation and ethnic group who originate from the Island of ireland and its. Associated islands ireland has been inhabited 9,000 about 9000 years according to (archaeological Studies See). prehistoric irelandhe terms Irish and Ireland are derived from the goddess Ériu. ériu a variety of historical ethnic groups have inhabited the, island including The, Airgialla Fir nEchmacht, Nechmacht, Delbhna Fir, Érainn, Erainn, érainn, Eoganachta, Eóganachta, mairtine Conmaicne. soghain and ulaid