The invasion of new tribes known as Celtic tribes went on from the 8th-7th cc. BC to the 1st c. BC. The first Celtic comers were the Gaels to Wales, Scotland, Ireland and Cornwall taking possession of the south and east. Thus the whole of Britain was occupied by the Celts who merged with the Picts and Scots, as well as with the Alpine part of the population: the latter predominated in the West while the rest of the British Isles became distinctly Celtic in language and the structure of society. The Gaelic form of the Celtic dialects was spoken in Caledonia (modern Scotland) and Ireland, the Brythonic form in England and Wales. The social unit of the Celts, the clan, superseded the earlier family groups; clans were united into large kinship groups, and those into tribes. The clan was the chief economic unit, the main organizational unit for basic activities of the Celts, farming.
This Celtdominated mixture of Picts, Scots and other ingredients came to be called Brythons, or Britts.
The Celts of the British Isles were heathens until later invaders, the Romans, brought Christianity to them. Their religion was a weird mixture of heathenism, that is the worship of certain Gods and Goddesses, with the worship of the Sun and Moon, and of the Serpent, the symbol of wisdom. The priests were called Druids, and their superior knowledge was taken for magic power. The Druids themselves must have been well pleased with this sort of reputation and enhanced its spell holding awe-inspiring vigils and observing terrible night rites in open air temples arranged somewhere in dark woods called Sacred Groves. The rites were associated with bloody sacrifice usually of animals but sometimes human beings, which increased the Druids’ power and authority over the masses. On the eve of the Roman conquest the Brythons were at the stage of decay corroding the primitive community structure; elements of a new, class society were appearing, with patriarchal slavery as a new feature. The rapid economic development of that time led to a weakening of the Celtic clan structure and that to a certain extent may account for the comparative ease with which the conquest was effected.
