The Celts, according to some scholars, a group of peoples, for others a race, spread throughout Europe, contributing to the constitution of several other nations. The core of its location was probably Germany, but the so-called continental ones spread through Hungary, Greece and Asia Minor. They never formed a homogeneous bloc, but rival tribes, who did not even worship the same deities, with the exception of a few common entities.
The inhabitants of the islands were spread across Great Britain and Ireland. It is generally to them that literature refers to mentioning the Celts. Belonging to the Iron Age, they formed small villages commanded by chiefs who also led combat. There are no written documents about the continental Celts, but their gods became known to the Romans, who assimilated many of their gods to the Celtic deities.
The peoples of the United Kingdom and Ireland also bequeathed to posterity a rich mythological complex, transformed into a literary work in the medieval era. It is customary to divide Celtic mythology into three classes, according to the beliefs associated with them - Goidélica, Irish and Scottish; British Insular, Welsh and Cornwall; and Continental British, Continental Europe.
Little is known about the Celtic gods, often not even as they were actually named. Among them, researchers know goddesses who govern natural phenomena, such as Tailtiu and Macha; Epona, goddess related to horses; Goibiniu, the beer producer; Tan Hill, Celtic equivalent of the entity linked to Fire; Cernunnos, Slough Feg or Cornífero, Latinized version, is one of the oldest, but history is ignored. There are also diverse forms of the same deity, depending on the region she is worshiped.
It is a common belief that the Celts worshiped their deities only in the open air, but it has recently been proven, through archaeological excavations, that they were in the habit of building temples, and after the invasion of Rome, they began to find sacred buildings with Celto-Roman characteristics.
In the beginning, however, the Celts were really limited to worshiping their gods on altars built in woods. They even elected certain trees as divine beings. The highlight given by the Celts to these elements of Nature, who even lent their sacred names to the Celtic tribes and characters Irish myths - Mac Cuillin, ‘son of acebo’. Only later, with Roman inspiration, did they start the building of temples, a custom left to the Germans, who succeeded and surpassed them in this art. the research already carried out, it is concluded today that human sacrifices, so commonly attributed to these peoples, were very rarely practiced.
To conclude, one cannot forget the importance of druids, a hereditary category of shamans - priests or sorcerers who held the power of healing - common in all Indo-European societies of antiquity. Thus, they were widely qualified to exercise magic, sacrifices and divinations. Many elements of Celtic culture and druids can be found in the work “The Mists of Avalon”