The Motagua River flows down from the western Guatemalan highlands, and Quiriguá was ideally positioned to control the trade of uncut jade, the majority of which was found in the middle reaches of the Motagua Valley, as well as controlling the flow of other important commodities up and down the river such as cacao, which was produced as a local cash crop. Although cacao was produced for trade, maize remained the primary local crop due to its central role in the Maya diet. In addition, maize probably formed an important component in the site's tribute payments to its overlords at Copán, a city that was exhausting its own local resources. Although little jade has been recovered from the site, there is evidence for trade in obsidian originating from the Ixtepeque source situated near the upper reaches of the Motagua.