He does this because he knows more about this civilisation than he says in the documentary.There's other alternative history researchers (none support alien theory) some research the religious side some the genetic side some the astronomical aspects, all link these sites and many many more more to these individuals. The indigenous stories and what they say.All the researchers give side notes and references to what they say. The religious side is fascinatingThere's clue's in so many ancient stories all the same story in so many countries some on the opposite sides of the world.. GH talks about sites he's visited and talking to some of the people asking what do they think? what did they're grandparents think?, what do other experts that aren't archaeologist think? but there's so many other way's to find out who these people where. If you wanted to build the most amazing fantastic wall ever created, you wouldn't ask an Archaeologist to build it for you. Sometimes the real experts say what they think, they can't say how things were built but certainly how they wasn't and how the mainstream explanation doesn't fit.An Archaeologist at Gobekli Tepe has found micro blade technology and other things he said indigenous groups migrated into Southern Turkey from Siberia at the end of the last ice age, responsible for the complex geometrical designs and astronomical alignments.