The area designated by the vague term 'Upper Amazon' is actually incredibly extensive. The great Amazon system drains three million square miles of territory, or approximately half the South American continent. Some of it's most remote tributaries, fed by melting glaciers in the Andes, originate less than eighty miles from the Pacific coast. Others extend upward into the highlands of Venezuela, Colombia, Ecuador, Peru, and Bolivia. This vast area, flanking the eastern slopes of the Andean chain, embraces a bewildering number of Indian tribes, an almost unbelievable number of unrelated languages, and a series of tropical forest cultures that range from exceedingly simple and primitive to highly sophisticated and complex... Harry Tschopik, Jr.