Celts are many different various individuals and countries whom settled in a big section of europe relating to the Iberian Peninsula and Britannia. They would an homogeneous faith, but always were politically split. The larger understood ethnic group could be the Gauls. Fierce and hard-fighting, in 386 B.C. the Senones Gauls led by Brennus spot Rome under siege and occupied it. They were down the road subjugated by the Romans.