Caesar tells us that the Celts were a very religious people, but it is difficult to piece together the evidence for the deities, the sources are confused and muddling. For instance it is not clear whether there were many localised gods or one main deity with a number of aspects. The evidence points both ways. Looking at the epigraphic record we can see over 400 god names mentioned of which 300 are mentioned only once. This would seem to indicate strong localisation. On the other hand there are is a commonality to be seen in the widespread distribution of some of the god forms e.g. horned deities, triple goddesses and mother figures and in the wide spread veneration of natural places.
The Celts had a strong belief in the afterlife, a fact demonstrated by both the literary and archaeological sources. Caesar tells us that the Celts believed in an ancestor god who he identified with Disapater, the Roman god of the dead. Diodorus Siculus tells us that the Celts perceived men's souls to be immortal and that after a number of years they would live again inhabiting a new body.
The Welsh Otherworld was called Annwn or Annwfn and was described as a place of pleasure and plenty with meat, drink, gold and jewels in abundance. Annwn is is also associated with a magical cauldron, a vessel of regeneration and fertility. The Irish Otherworld is in many respects similar to Annwn, a place of happiness, harmony and plenty. It was known as Tir na n'Nog (the "Land of the Forever Young"). It was possible for the living to have contact with the spirits of the Otherworld at Samhain, a dangerous time , when the veil between the living and the dead was very thin and spirits and humans could move into each others worlds.
Archaeological evidence supports the literary evidence regarding the Celts belief in the afterlife, and a number of burials have been found with associated grave goods, suggesting such an expectation. European and British sites have yielded burials with chariots, weapons and feasting items (including amphorae, firedogs and wine cups). The best known group of burials in Britain occur in Yorkshire (generally known as the Arras tradition - named after the cemetery of the same name) where many         inhumations have been  discovered using aerial photography and excavation. The graves here are mostly found under barrows with round or square ditches, along with some flat graves. At least ten of the Yorkshire burials have included vehicles and at Garton Slack the dead man