There's supposed to be a setting that alllows you to set the initial era, giving civs all the techs from previous eras. Unfortunatlely, I haven't been able to find out where it is. The help file is useless in this case; all it tells me is what it does, not where to find it.
__________________
... And on the pedestal these words appear: "My name is Ozymandias, king of kings: Look on my works, ye Mighty, and despair!" Nothing beside remains. Round the decay of that colossal wreck, boundless and bare, the lone and level sands stretch far away ...