Comment by nephihaha

"This is one of the problems with what the Celts did: they didn't write."

That is a common misconception. We don't have much in the way of ancient Celtic writing, or even enough, but we do have some . The best known example is the Coligny Calendar. Some of the Celtic peoples used the Greek script and variants. There is also debate about how old Ogham is (although AFAIK there is no evidence of it from Hallstatt and La Tene).

I would not be surprised if some pre-Roman Celtic writing does turn up from this region at some point.