This 1915 volume recounts Captain Thomas Whiffen's travels in Brazil and Colombia in the region between the rivers Issa (or Içá) and Apaporis, and the Putumayo District. The study looks at the way in which the indigenous peoples, especially the Boro and Witoto, relate to their land. He describes their way of life, including their homes, agriculture, food, weaponry, warfare, clothing, health and medicine, songs and dances, magic and religion, tribal organisation, the social status of women, and their reaction to strangers. The practice of cannibalism is also addressed and Whiffen suggests some possible reasons for it, including vengeance and supreme insult to enemies, the need to consume all available meat, and the desire to adopt some characteristics of the dead. Appendices include detailed lists of the Native Americans' physical features, deities, vocabulary, and names, and an example of tribal poetry.