There are plenty of legends out there from different tribes, however the most known would be from the Kaxianawá tribe in the northern Amazon basin of Brazil. The legend has it that the native of the tribe were very ill and the Pajé/medicine man had tried everything to cure them, without success.
In an Ayahuasca ceremony, he went into the jungle and was visited by a female spirit of the forest. She was holding a frog in her hands, from which she took a white secretion and taught the Pajé how to apply the medicine. After returning to his tribe and following the guidelines, the Pajé was able to cure his sisters and brothers. From then, he carried the name Pajé Kampu or Kampum.