...And why they were so hard to see. The Amazon has always been one of the most mysterious places on earth. When European colonizers arrived in the 16th century, they were captivated by rumors of a golden city, hidden somewhere in the rainforest. Their search for "El Dorado" lasted more than a century, but only resulted in disaster, death, and further conquest of the indigenous people there. Experts thereafter looked at the Amazon and saw only a desolate jungle; too harsh for extensive agriculture and therefore sparsely populated. They believed that it had alwavs been this way. Until recentlv.