The setting for "The Lost World" is believed to have been inspired by reports of Doyle's good friend Percy Harrison Fawcett's expedition to Huanchaca Plateau in Noel Kempff Mercado National Park, Bolivia. Fawcett organised several expeditions to delimit the border between Bolivia and Brazil – an area of potential conflict between both countries. Doyle took part in the lecture of Fawcett in Royal Geographical Society on 13 February 1911 and was impressed by the tale about the remote "province of Caupolican" (present day Huanchaca Plateau) in Bolivia – a dangerous area with impenetrable forests, where Fawcett saw "monstrous tracks of unknown origin".