The Tepanex tribe controlled a critical resource that led to conflict with the Aztecs. What was it?

The Tepanex tribe held control over vital water sources in the valley, which were essential for sustaining agriculture and supporting the population in the region. Given the agricultural practices in Mesoamerica, access to reliable water sources directly impacted crop yield and food supply. This scarcity of water would have created tensions and conflicts with neighboring groups, including the Aztecs, who were rapidly expanding their territory and seeking to secure resources for their growing civilization.

While gold mines, land for agriculture, and sacred temples are all significant resources, the immediate and practical necessity of water sources for irrigation and daily sustenance made them particularly critical in the agricultural context of the valley. Control over these water sources would have given the Tepanex considerable leverage, prompting the Aztecs to vie for control of these essential resources.