Celts are a variety of various peoples and countries whom settled in a sizable section of europe involving the Iberian Peninsula and Britannia. They would an homogeneous religion, but always were politically split. The higher known ethnic group is the Gauls. Fierce and hard-fighting, in 386 B.C. the Senones Gauls led by Brennus place Rome under siege and occupied it. They were later on subjugated by the Romans.