The Guaraní in the Chaco region put up long-lasting resistance to conquest and colonization. Recurrent hostilities characterized the relations between the Guaraní and the Spanish Crown and, after Independence, the Bolivian state; the region in the eastern part of Charcas, not far from the capital La Plata or Sucre, is known even today as “the Frontier.” In South America, this resistance is comparable only with that of the Mapuche in southern Chile.

We do not know how far back this myth dates, but it was recounted by a Franciscan missionary from Italy, Doroteo Giannecchini, in a written account in 1898....