It’s not like some of the historical crucis here can’t be Helenic or Carthaginian. I don’t see much attention to the specifics of Roman history outside of certain threads. Plus, there not much technology present. A naked woman, a cross, and some crude nails could be any time between 2000bc to 2018ad. It just seems that the middle of that range is popular for some reason...
(Maybe even earlier than that, actually. No telling if the Summerians practiced crucifixion or not. You could plausibly stretch back as far as there were stole tools and behaviorally and anatomically modern humans. I wonder who the first crucifixion victim was?)