I'll look up the material -- and thanks! But my question still remains -- what evidence is there that in 1800 BC and **earlier** that there were accurate sky maps, accurate tables of planetary movement, and accurate calendars? I know about the material that occurred in Ptolomaic times (at least I know it exists. Details, I don't know.)

But what's being claimed is something that involved things that are far older than Ptolomaic times and that's why I'm raising the question of who knew what and when.

Could you point me to some evidence of this earlier knowledge?