The region is subject to prolonged and severe droughts and seasons of disastrous heavy rains. Hail and winds also impact crops. In the Titicaca basin natural resource distribution is very much a function of altitude. The Altiplano became exploited by humans after the Pliestocene. These camelids graze on the higher elevations, allowing exploition of areas unfit for agriculture.
Agriculture is only feasible in the lowest elevations of the basin.
Additionally, the 8,600 sq. km. Raised fields, which also mediate ambient temperatures and protect against frost, date to 850-600 B.C. around the lake. Additionally, raised fields are a sustainable, continuous system that does not require fallow and produces higher yields than regular cultivation. A basin wide tradition of monumental architecture and sculpture antedating Tiwanaku developed. 1300-1200 B.C. This first case of organized corporate construction of monumental stone architecture follows the suceeding pattern within the basin, being situated near the lake.