And they: - Didn't affect the atmosphere in any way. - Had all their buildings were recorded as being built by a people we know much about in specific timeline

And they: - Didn't affect the atmosphere in any way. - Had all their buildings were recorded as being built by a people we know much about in specific timelines we know much about, which aligns with archeological artifacts. - Made sure none of their lithics stayed. - Used no fuel source. - Did no mining of any kind. - Never used anything but stone and paper machete for building (because even wood structures leave identifiable patterns for potentially thousands of years). - Only used that stone for a couple buildings, which they planned for the cultures that didn't exist to use intimately. - Had their bones dissolved without a trace. All we have to do is remove any type of evidence-based science and anything is possible!