These earthworks may be the only things remaining of the local tribes that inhabited the area. The question is if these works were done at a time the Amazon was a densely packed forest/jungle, or it was different and since the disappearance of their makers, the jungle took over.
It’s recorded by the first European settlers that the land was rich in food that could be collected by the forest. In reality the native people practiced silvicuture and selected better trees for food like cacao and they would collect fruits/seeds from the vegetation planted hundreds of years before without damaging the forest, just making genetic modifications. Some traditional groups still make this kind of selection nowadays
