However, altitude is not the only factor determining the environmental conditions of the puna. A major influence on these rolling grasslands, streams, and plains is weather, especially rain. It is generally a cold, moist, largely non-seasonal climate, especially in central Peru. The puna zone lies between the steep, western slope deserts and the hot, forested eastern slopes that run down into the Amazon Basin. Interspersed among puna stretches, and about 1000 m lower are highland valleys, with warmer climates more appropriate for agriculture. Some parts of the Andes, especially in northern Peru, do not really have a puna zone, as the mountain chain is dominated by major high valleys.
Besides the bunch grass that covers most of the puna altiplano, several other plants are found in the area. Berries, tubers, and a variety of seed-producing plants can be found distributed across the puna, but grasslands are the predominant ground cover. Although the land seems to offer little natural protection for early people, some natural shelters are part of the landscape. These are the typical caves or rock shelters as seen to the left. To survive frigid puna nights, and to avoid the heat-robbing effects of rains, some form of shelter would be essential.
The puna zone grasslands are excellent for grazing and are home to a number of species of camelids: the llamas and their relatives. It is likely that the people occupying the larger, continuous regions of the puna environment would be able to obtain adequate resources to remain there year round. The major game animals are present throughout the year and various plants could have supplied a modest amount of vegetable food through the seasons. In the dry season (June to September), carbohydrate rich tubers and seeds are move available, with leafy plants more common in the wet season (December to March).
Excavations have yielded insight into the occupation of the puna. Pachamachay (seen left) showed a pattern of base camp use while several surrounding temporary camps, were probably used sporadically as local sites to support hunting. Good evidence that the puna occupation was year-round comes from evaluating the remains from base camps. There is little evidence of the use of non-puna cherts, plants, or animal foods which could be expected if the people moved seasonally between the puna and other environments like the highland valleys. Also, there is evidence of camecamelid and plant utilization from all the seasons of the year. So it seems that an apparently harsh environment like the puna could provide an adequate home for the people of the Preceramic Period.