About 2500 years ago, and possibly long before that, at each end of the Indo-European arc, tribal spiritualities emerged that would eventually grow to become flourishing modern movements, with adherents all over the world. While the earliest versions of what would later become the Hindu and Jain religions emerged in the Indus valley, in western Europe at about the same time, writers began to record the existence of Druidism.
Its practice was first noted in two Greek works over two thousand years ago in around 200 BCE although both works were since lost. In 50 BCE Julius Caesar wrote that Druidism originated in Britain, and although some claim that Druids could be found across much of Europe, from Ireland in the west to Anatolia (now Turkey) in the east, scholars now believe this is unlikely. Instead Druids were probably native just to the British Isles, Ireland and western Gaul (now France).
Although written accounts seem to have begun 2,200 years ago, Druidry was probably in existence for a good deal of time before then, and it seems likely that as a type of religion or magical practice it evolved out of earlier pre-Druidic cult practices.