Britons

Also in briton the ancient folks have lived there for many thousands of years. They only grew important to the rest of Europe after the celtic invasion, when the Iron Age first was introduced to those islands. They could expand and slowly build up an empire.
During this invasion the Britons ended up changing their culture to the costums of the Celtic people, they got to live in smal communities then, bound together by their religious believes and similar language. They were warriors, living for the glories of battle and plunder.