A clear process of religious Romanisation is evident at longstanding Celtic sites such as Bath. In fact, so evidently profound were the changes to cultic traditions under Roman rule that much of what is known today about ancient British and Gaulish religion might rather be understood as Romano-Celtic. Not only were indigenous divinities brought into the Roman pantheon through a form of cultural syncretism, but substantial changes in the ceremony and thinking surrounding Celtic funerary traditions also appear to have occurred under the Empire. Romanisation did not always mean the slavish adoption of Latinate beliefs and practices, however, as the Roman world was cosmopolitan – many aspects of religious Romanisation were as Greek or even Etruscan as they were originally Latin. In fact, the Gauls had been in contact with Greek and Etruscan colonists for centuries before the arrival of Caesar's legions in the 60s BC; the modern city of Marseilles, for instance, was founded by Greek colonists at a time when Rome was still under the rule of Etruscan kings. Moreover, these early contacts are reflected by epigraphic evidence – by texts composed in Celtic adaptations of both the Greek and Etruscan alphabets.

The earliest inscriptional evidence for Celtic language stems from the Alpine regions, and many of these Etrusco-Celtic texts are funerary in nature. Such finds range from very short inscriptions which feature little more than early Celtic names to a short poetic memorial (from Vergiate, Lombardy) which seems to reflect a type of funerary text better known from more southerly parts of the early Italic world. Contemporary archaeological evidence such as tombs covered by burial mounds and rich graves containing inhumed chariots are complemented by short funerary-stone inscriptions which feature indigenous technical language such as verbs for ‘setting up’ and ‘raising’ memorials as well as various early Celtic words for ‘tombstone’ or ‘cairn’. There seems to have been a very early and widespread tradition in ancient Celtic society that certain people should continue to be recognised after their deaths through lavish burial customs and that tombstones should be raised for others in a manner more typical of contemporary Mediterranean funerary practice. But such finds present little more than hints of what the early Continental Celts might have held happened to mortals, men or women, rich or poor, after they had crossed the threshold of death.