There is not a lot of tutorials on that because it is really hard to do. If your going to do procedural generation of civilisation, monsters and characters, then you would need to do some terrain generation. So you could start there.
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On civilisation, understanding the most simple civilisation is hard work. There an interesting free course on this https://www.coursera.org/learn/organising-empire-assyrian-way where even Assyrian empire is really complex. It also describes how terrain plays a bit part in a civilisation.
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There is some interesting academic work. https://www.youtube.com/watch?v=VwvjBbh05ts some of his work is interesting if you want to model realistic religions.
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My advice pick a civilisation that interest you. Try to break it down into procedural rules. Then iterate.