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I want to have a society that is very isolated (physically) and has been for long enough that it doesn't really believe that there's anyone else out there. I also don't want the society to be in any way motivated to explore outside of its area. General background info about society (still up for change): The land where the people live is warm and fertile. They live in a river valley surrounded by mountains except at one end, where the river flows out. The society itself is matriarchal and has a polytheistic religion. There is one government, a monarchy lead by a queen but that also has a small aristocratic class. Most of the people there are farmers, fishing people, or artisans. There are other people who live not too far away on the other side of the mountains, but the occupants of the river valley are unaware of their presence.