Firbolgs – Ui Failge, Ui Bairrche, Ui Enachglais

The Euerni and later called Erainn (also known as Menapii, Bolgi, Belgae and Firbolgs) by annalists and historians, arrived after ???? BC. They called their new home Eueriio, which would later evolve through the old Irish Eriu to Eire, and from Eire to Ireland.
The early annalists tell us that Firbolg people survived as distinct tribes well into early historical times. In Leinster, they were the Ui Failge, Ui Bairrche and Ui Enechglaiss to mention but a few.
Source: http://www.thecore.com/let-ros/plavin/lavin.html