Fir Bolg
The name may be based on, and cognate with, Belgae. The Belgae were a group of tribes living in northern Gaul. Some have suggested that the writers named a fictional race, the Fir Bolg, after a real group, the Belgae. Others, such as T. F. O'Rahilly, suggest that the Fir Bolg, Fir Domnann and Fir Gáilióin were historical peoples who reached Ireland in ancient times. He proposed that the Fir Bolg were linked to the historical Belgae, the Fir Domnann were the historical Dumnonii and the Fir Gáilióin were the Laigin.