Written data about the Mashco and the Madre de Dios area come from post-Conquest sources. According to these sources, the following historical periods can be demarcated: pre-Hispanic; Viceregal; rubber-tapper incursions at the end of the ninteenth and beginning of the twentieth centuries; and the establishment of missions, colonization of the territory, and present-day situation (from 1950 on). The Inca endeavored to extend their dominion to the eastern slope of the cordillera, giving that unexplored section of its territory the name "Antisuyo." Around 1430 in Inca chronology, people of the sierra began their slow infiltration from Paucartambo toward the east.
In an eloquent text, Garcilaso de la Vega ("el Inca"), the Hispanic-Indian chronicler, narrates how the Inca Roca decided to send his son to conquer the Antisuyo; for this enterprise he had 15,000 warriors. Likewise, in 1450 the Inca Yupanki decided to conquer the Mojo and penetrated the Kosñipata Valley. His men, estimated to number around 1,000, were annihilated by the "Chuncho," who can have been none other than the Mashco. The Quechua called the upper Río Madre de Dios "Amáru Mayo" (Snake River)—because of its winding course—or "Mayu Tata" (Father of the Rivers)—because it is the source of so many rivers. One of the reasons that motivated the Spaniards to penetrate this Amazonian area was the legend of Paititi or El Dorado; they began their incursions toward the end of the first half of the sixteenth century. Among the most important ventures were those of Juan Alvarez de Maldonado, who in 1566 and 1567 made two expeditions, fought with the "savages," and returned with tales that only heightened the interest in reaching Paititi.
Some scholars and travelers visited the area in the republican era, and Father Bovo de Revello, an Italian Carmelite, was responsible for changing the name of Amaru Mayu to Madre de Dios after finding an image of the Holy Virgin on a rock. The image, which had fallen victim to indigenous sacking, had been thrown into the river and was seen by the Christian neophytes on Ascension Day. Rubber-tapping expeditions contributed nothing toward knowledge of the Mashco; instead, they brought only blood and death. In 1902 two important events took place that gradually contributed to pacification and knowledge about this ethnic group. One was the setting up of a missionary post by the Dominican order, which established contact with the Wachipaeri and led to the evangelization of the Kosñipata Valley. The other was the founding of the city of Puerto Maldonado on the lower course of the Madre de Dios, in the vicinity of its confluence with the Tambopata.
From then on, the area was to be the base from which all attempts at catechization were to be undertaken from the north. The Dominican missionaries began an intensive study of the Mashco language and wrote ethnographic descriptions that slowly informed the scientific world about the Mashco and their respective factions. With the publication of this information, linguists and ethnologists began their work, creating an extensive bibliography. Mashco groups have had permanent confrontations with each other, which on occasion alternated with alliances to fight an adversary faction that was more numerous and warlike. Relations with neighboring groups—for example, the Machiguenga from the Pantiacolla ranges—were far from peaceful. The traditional enemies of the Mashco, however, have been the so-called Amiko; that is, foreigners of European origin.