Lost Ancient civilisations That's always a hot topic, sometimes leading to less scientific ideas and indeed it's hard to keep it on the straight and narrow path. If only we knew which path that was; hence heated debates. The aim of this thread is to find that path and stay on it, although I realise that this ambition is rather far fetched. Anyway, the essential question here appears to be: Moonbear added some valuable notes. But the question still seem to stand, why didn't that happen 5-10kya, or something, after the appearance of H. sapiens? SelfAdjoint has a good point too: And it's evidence that count. Not our imagination of course. Now it's getting really delicate but I agree there are a few (more or less disputed) features that may point to unknown ancient civilisations indeed. Like: http://www.asahi-net.or.jp/~yf5f-wtnb/moai_idx/tongariki/moai6_04.jpg http://www.civilization.ca/civil/egypt/images/arch25b.jpg http://www.marsearthconnection.com/cuba.html, discussed here So, what else is there to say? Could there have been unknown civilisations like the Egyptian, Greek or the Roman empires but say anywhere around 150,000 years ago, give or take some 50,000 years?.