The basic question being how can I get a society in the medieval era of technology co-exist with a society closer to the stone age of technology? I have two distinct cultures I am trying to flesh out and a third one on the way for this planet I am working on. But I want slightly more dynamic societies and am having trouble justifying them both being on the same planet and not being in line with each-others advancements.
One society is like Gothic medieval Europe, with knights and castles and a church based system all generally situated in the mountainous areas. The other is more tribal, living in nature and worshiping a number of spirit/deities with tribal tattoos and rudimentary weapons situated in the forests and more densely fauna areas.
I am considering race differences or slight species-based gaps, or maybe they are at odds as cultures ( preferably not full-blown war but I'm not entirely against the idea).
This is my first question on this forum/page so If the question is too broad or doesn't sit in the guidelines just let me know. Thanks for looking/answering!