Although the Amazons have been known to Europe for fully four hundred years, exploration has been confined almost entirely to the main river and its great tributaries. Little addition has been made to the information possessed by Sir Walter Raleigh in the three hundred years that have elapsed since his death. The rivers certainly are known and charted, yet the land beyond their banks is almost as much a land of mystery in the twentieth century as it was in the days of Queen Elizabeth. It is possible to spend a lifetime in navigating the Amazon, and to know nothing more of its 2,722,000 square miles of basin than can be peered at through the curtain of vegetation which drapes the main streams. Behind that veil lies the fascination of Amazonian travel.

We are not here concerned with the scanty records history offers of these vast regions, nor, for our immediate purposes, is it needful to inquire into the conditions and features of the Amazon watershed as a whole, except in so far as they differ from or resemble those of my field of exploration, the tracts between the middle Issa and Japura Rivers, and in their vicinity. Roughly speaking, this lies in that debatable land where the frontiers of Brazil meet those of Peru, Colombia, and—perhaps—Ecuador, a country claimed in part by the three latter, but administered by none.