I think I read that most ancient civilizations collapsed because of environmental factors. The environment changed, and they couldn't cope with it for some rea

I think I read that most ancient civilizations collapsed because of environmental factors. The environment changed, and they couldn't cope with it for some reason (lack of technology was probably a big part). As for China, I don't think that one ever "collapsed". It withdrew, but I don't think you can call it a "collapse" the way many other ancient civilizations did. Even Rome is a bit hard to call a full collapse: it degraded over the course of centuries, and eventually Europe turned to feudalism. The Roman Empire itself split apart, with the eastern part (in Constantinople) continuing for another 1000 years after the western side fell apart. I think civilizations like the Assyrians and Hittites are better examples of civilizations that truly "collapsed": there's basically nothing left of them today, except some ruins.