Extraterrestrials  visited  our  Earth many  millennia  ago.  They  behaved similar  to  how  current ethnologists behave  today.  They studied  a  few  languages, visited  different tribes,  gave  suggestions  and disappeared sometime-however, with the   promise   to return  in  the distant  future.  Our  Stone  Age ancestors  could  not  grasp what  happened  back  then.  They wrongfully  believed  that the extraterrestrials were  gods.  The  supposed  then wandered  into  our mythology  and  became  the founders  of many religions.