By mid-1966, Debray was in Bolivia with credentials as a correspondent from a Mexican magazine, Sucesos, and the French publishing house Maspero. He was, in fact, however, assisting in the arrangements for Guevara's insurgency, and in September he began a study for Havana of the merits of certain potential locations for the revolutionary foco. Those locations he and a group of Cuban colleagues originally considered lay in another region entirely than the spot Guevara eventually chose. The team seriously viewed but quickly discarded one site when it was discovered to be within easy range of a military base, but several other locations had much to recommend them. They lay deep in the mountain range but still much closer to La Paz and Cochabamba than the place finally selected. That site, which has come to be called Nancahuazu, was far into the wilds of southeast Bolivia near the Nancahuazu River, where, in fact, the guerrillas already had bought a farm.
Pombo, one of those who made the purchase, says Guevara originally intended the Nancahuazu location to be a rear base for organizing and training the band, which then would operate "a little farther to the north" in an area of "taller vegetation, a higher population density, and better conditions." When that time came, Guevara planned to move the base camp to the region of the upper Chapare River. He also intended to have a link with Argentina through the eastern ranges of the Andes, says Pombo. Premature discovery of the camp by the army, however, changed those plans completely, locking Guevara into operating further south than he had intended.
Debray says he lamented the decision to go to Nancahuazu. The site was too far from any urban center that could support the guerrillas and too far from populations with animosities toward the government that might help in the struggle. Nevertheless, Guevara decided on it in October, in large measure, says Debray, because by then the Communist Party knew that Bolivia was to be the center of the insurrection and also knew which sites near La Paz were being considered for the base camp. The party, strongly opposed to the undertaking, became even further irritated because Debray and the Cubans were negotiating for support with a despised radical splinter faction, headed by Moises Guevara. Fearing that the Communist Party would betray him, says Debray, Guevara opted for the security of the more inaccessible site, which had the added advantage from his point of view of being closer to Argentina.
Monje told Guevara biographer Jon Lee Anderson a different story. He said he selected the site with Guevara's advance team almost arbitrarily because it was near Argentina, where he assumed Guevara was headed.