The first Spanish explorers who sailed down the Amazon from Peru reported that the riverbanks were densely populated and under intense cultivation. I suspect European diseases caused the collapse of these societies and the floodings of the River washed away the structures.
"The first Spanish explorers who sailed down the Amazon from Peru reported that the riverbanks were densely populated and under intense cultivation. I suspect European diseases caused the collapse of these societies and the floodings of the River washed away the structures." Yup. The Amazon River was named after the female warriors (Amazons) seen on the banks of the river.
Furthermore, hundreds of miles of canals and raised fields are still visible from the air. It is estimated that when the 'modern' Europeans discovered South America, there were more humans living in SA than all of Europe. Teotechuan(sp) was larger than London.