It’s History Channel doing anything but teaching History. Sad. Only misinformation and conspiracy documentaries are all people want to make but when a real documentary comes along, it blows them all away (shoutout to Ken Burns).
This doesn't pass the sniff test. How could a civilization supposedly far more advanced than the Inca vanish without leaving the Inca a single shred of evidence of their existence? No tools, no records, no memory at all? Oh, except the giant intricate stone structures they built. A coordinated conspiracy to claim their superior civilizational achievements as their own might be the only explanation of that and that's veering into comedy.
Well, there's obviously the alien contact theory. If you've ever been to Nazca where the landing strips are only a few hundred miles from the Inca empire you'd be a believer. If you want to believe, that is.