During the first fifteen years of the present century, the production of rubber from wild trees was a thriving, though nefarious, industry in the northwestern part of the Amazon Valley. The heaviest concentration of this primitive forest industry — and the most widely notorious — was centered in the area drained by the Rios Karaparana and Igaraparana, northern tributaries of the Rio Putumayo, lying between the Rios Putumayo and Caquetd (Map 1). In this hey day of rubber production, the area was claimed by both Colombia and Peru, but the Peruvians actually occupied and exploited it. As a result of the war between Colombia and Peru in the early 1930’s, the boundaries have been set with the Rio Putumayo as the frontier. Colombia is now in possession of the areas north of the Putumayo, which are incorporated into the Colombian political unit known as the Comisaria del Amazonas.