Adventure, heroism, romance, and magic are a few of the elements that make Celtic mythology one of the most entrancing mythologies of Europe. Once a powerful people who dominated much of Europe, the Celts were reduced to a few small groups after the Roman invasions. However, their mythology survived, thanks largely to the efforts of medieval Irish and Welsh monks who wrote down the stories.
Celtic expansion reached its limit around 225 B.C., when the Celts suffered the first in a series of defeats by the armies of the Roman empire. Gradually, the Romans subdued the Celts, and by A.D. 84, most of Britain was under Roman rule. At the same time, Germanic peoples conquered the Celts living in central Europe.
Just a few areas, notably Ireland and northern Britain, managed to remain free and to continue and pass on the Celtic traditions. Six groups of Celts have survived to modern times: the peoples of Ireland, Scotland, the Isle of Man, Wales, Cornwall, and Brittany.
The ancient Celts were neither a race nor a nation. They were a varied people bound together by language, customs, and religion rather than by any centralized government. They lived off the land, farming and raising stock. No towns existed apart from impressive hill forts. However, by about 100 B.C., large groups of Celts had begun to gather at certain settlements to trade with one another.
Celtic society had a clearly defined structure. Highest in rank was the king, who ruled a particular tribe, or group of people. Each tribe was divided into three classes: the noble knights and warriors, the Druids (religious leaders), and the farmers and commoners. The Druids, who came from noble families, were respected and influential figures. They served not only as priests but also as judges, teachers, and advisers. In addition, it was widely believed that the Druids had magical powers.
Some deities had more clearly defined roles. Among these were Lug, or Lugus, a sun god associated with arts and skills, war and healing, and the horned god Cernunnos, who was god of animals and fertility. The Celts also had a large number of important female deities. These included Morrigan, the "Great Queen"—actually three war goddesses, Morrigan, Badb, and Nemain, who appeared as ravens during battle. Another important deity was Brigit, goddess of learning, healing, and metalworking. Epona, the horse goddess, was associated with fertility, water, and death.