Annual festival.

Dude, secretly, behind the wall is a normal, developed society that, for some reason, needed to conduct an experiment with a post-apocalyptic society and castes. Yep.

Siv, well, they aren't divergents either. Just limited people who decided to rule over other limited people, without thinking about the consequences. It's all logical, although not reasonable.

Strangely enough, a similar thought occurred to me while reading. But I probably wouldn't want to live in such a world.