I thought you were just doing vanilla DF, but instead of 14th century you play in the stone age?
That was the intention, but, I don't feel simply changing what weapons are made from is enough to justify the theme. I'm going to try and devolve civilisations and creatures prior to what they might have been if you were to retract 9000-10000 years, and a lot can change in that amount of time.
Also, thank you for the information. It is very helpful.
If you wanted to really mess things up, you could have Goblins be the most advanced race at the time (Early bronze age style tech) and give them a less chaotic (but by no means less brutal; most everything could be punishable by execution and society can still be built on slavery) social order. The implication would be that Goblins are, by the 'modern day' in DF, experiencing something of a dark age; society has largely broken down.
You could use societies like the Garamantese or Mesopotamia as a theme.