Editing Coca (section)

===Ethnohistorical sources===
While many historians are in agreement that coca was a contributing factor to the daily life of the [[Inca]], there are many different theories as to how this civilization came to adopt it as one of its [[Staple food|staple crops]] and as a valued commodity. The Incas were able to accomplish significant things while stimulated by the effects of coca. The Incas did not have a graphical written language, but used the ''[[quipu]]'', a fiber recording device. Spanish documents make it clear that coca was one of the most important elements of Inca culture. Coca was used in Inca feasts and religious rituals, among many other things.<ref name="auto1">Mortimer, W. Golden. Peru History of Coca: "The Divine Plant" of the Incas. New York: J. H. Vail & Company, 1901.</ref> It was a driving factor in the labor efforts that Inca kings asked of their citizens, and also used to barter for other goods. Coca was vital to the Inca civilization and its culture. The Incas valued coca so much that they colonized tropical rain forests to the north and east of their capital in [[Cuzco]] so that they could increase and control their supply. The Incas colonized more humid regions because coca cannot grow above 2600 meters in elevation (coca is not frost-resistant).<ref name="auto">Valdez, Lidio M., Juan Taboada, and J. Ernesto Valdez. 2015. "Ancient Use of Coca Leaves in the Peruvian Central Highlands." Journal of Anthropological Research 71 (2): 231–58. doi:10.3998/jar.0521004.0071.204 .</ref>