The Inka Empire stretched along the Andean mountains, uniting lands as diverse as the high grasslands , fertile valleys, and dry deserts of the Pacific. As great builders and shapers of landscape, the Inka created storehouses for surplus crops and shifted supplies across the empire to meet local demands. In one regional study of the Upper Mantaro Valley, archaeobotanist Christine Hastorf has demonstrated a change in local production under pre-Inka Wanka II (earlier) period villages to the crops of the Wanka III (later, Inka period). During Wanka II, people lived in greatest density in the valley bottom, closest to fertile soils, where they grew root crops, like potatoes, and small-grained quinoa. In Wanka III times, populations dispersed to live on the upper slopes; the valley bottom now contained Inka storehouses, and the fertile fields at the