The Las Pircas phase was a florescent period of Preceramic culture in the Zaña and Nanchoc valleys. Throughout the lower and middle Zaña Valley, the hunter-gatherer lifeway of the El Palto phase continued, but in a portion of the middle and upper valley, a new lifeway emerged in the steep forested lateral quebradas, an area we refer to as the Nanchoc pocket or basin (Dillehay and Netherly 1983; Dillehay et al. 1989). Despite showing evidence of only sporadic and apparently unsystematic outside contacts, the Las Pircas phase in this area was a time of significant sociocultural change, including the adoption of a wider inventory of cultigens (Dillehay et al. 2007; Rossen 1991; Rossen et al. 1996). It was also a time of probable ritual cannibalism and garden magic, manifested by careful cutting and placement in pits of adult male bones and by the presence of quartz crystals placed in furrows. This was evidently related to the broad cultural changes brought about by the shift to a house gardening economy (Rossen and Dillehay 2001a,b). Principal changes of this period occurred in and around the houses and not in any public or communal setting (Dillehay et al. 1999), which took place late in the period and during the following Tierra Blanca phase.

The evidence of earlier pre-Las Pircas populations in the upper middle Zaña and Nanchoc valleys was discussed in the last chapter.