Personally, I didn't know that Celtia had a specific time period in here. (ie before Christianity). I also think that a lot of the newcomers may not be aware of it either. I did the Celtic cross because a lot of people identify with it and instantly think of Celtic tradition and lore regardless of what time period it is in here.

So what happened to Celtia after Christianity came? Do I suddenly become a Germanic now since my family is from Ireland and could date back to 1500's? If not, where do I fit in?