What I am asking is basically a document, or a mention of a discussion that ancient people had about future, and how they imagined distant future to be.
I'm not sure if anyone is formulating or researching a proper, specific answer for your question, but in the meantime: if you search on the word "future" in this sub, it comes up with a multitude of threads that you may find interesting. Not sure if any of them specifically talk about historical, forward-looking documents, but there appears to be a lot of information and discussion about historical views of the future from various time periods!