I think it is more that for best growth you need to be accessible for trade over long distances, but not so accessible to armies that want to pillage all the la

I think it is more that for best growth you need to be accessible for trade over long distances, but not so accessible to armies that want to pillage all the lands. This was the problem China had, any time civilization gets going you have some damn warlord just running around wrecking it all. But even when they do consolidate power the empire is too big to centrally manage and has to be extremely oppressive to prevent the next warlord from repeating the same trick. This stifles the economy and retards the growth of technology.