Lost Kingdom of Eldorado-- What really happened?

The current narrative is still very murky regarding what really happened to the High civilization that was spoken of in 1542 by the spanish conquistador Francisco De Orellana. Current historical speculation is that the amazonian immune system was obliterated by the spead of disease and hence the lost city disappeared in time. I’m not entirely buying this assertion. This lost civilization was extremely advanced with not only aerial observations(landing strips} but also architectural knowledge {roads and land constructs}. Most important is the fact that these folks were master farmers and understood the principles of growing and maintaining highly nutritious foods while developing the most sought after soil on the face of the earth to this very day{Terra Preta}! Over time we have learned the importance of nutrition and maintaining a healthy immune system. Ironic that today we are faced with “mysterious” Disease and a destruction of our healthy food sources and environment. Advancements in “Science” { I use this loosely} seems to be uncovering history that we once thought only a myth. Coincidence or are we possibly dealing with a inner earth species who thrives on messing with humanity. David Icke anyone? Perhaps we are seeing a very old playbook role out from the depths with a new twist? Lidar study reveals much more dense early urban Amazon settlements - UPI.com {Kingdom of El Dorado} Terra Preta, the Black Earth upon which Civilisations were Built - New Acropolis Library