A qullqa (Quechua pronunciation: [ˈqʊʎˌqa] "deposit, storehouse";[1] (spelling variants: colca, collca, qolca, qollca) was a storage building found along roads and near the cities and political centers of the Inca Empire.[2] These were large stone buildings with roofs thatched with "ichu" grass, or what is known as Peruvian feathergrass (Jarava ichu). To a "prodigious [extent] unprecedented in the annals of world prehistory" the Incas stored food and other commodities which could be distributed to their armies, officials, conscripted laborers, and, in times of need, to the populace. The uncertainty of agriculture at the high altitudes which comprised most of the Inca Empire was among the factors which probably stimulated the construction of large numbers of qullqas.[3]