It would be kool to add a low level monument with a bunch of naked trible men with bows and spears you have to kill. You could put them on there own island like the sentinels in india. I think it would be interesting to see and would be fun to kill a bunch of naked NPCs with bows. Have them with bows, spears, bone armor, bone knife, etc. Maybe one or 2 with a AK in the back but they suck shooting it. Once you kill them all you should be able to take all there resources. It would give you wood, stone, and sulfur.
Let me know what you think.