Who were the Celts?

The Celts were the diverse and widespread group that populated Europe during the Greek and Roman Classical period and from whom it is believed the Germanic tribes sprang. Celtic society, in all it's various tribal groups, was hierarchical and based on class divisions. There were three classes. The first was the ruling aristocracy, including the King. The second and most powerful was the intellectual class comprising Druids, poets, and legal experts called jurists. The Druids had their own universities and passed their vast knowledge on by rote (repetition to the level of perfection). The third class was the common people, including laborers, farmers and warriors.

It was when the Romans began encroaching from the south on the European Celtic groups and the (theorized) Celtic off-shoot Germanic tribes began encroaching from the east that Celtic groups spread to the northern coast of France and the British Isles (England, Ireland and Scotland) warring against, conquering and/or displacing the native Briton peoples.