Sierra Mixteca

The Sierra Mixteca is one of the oldest geological regions in the territory of Mexico.

During the emergence of the two Sierra Madre ranges, the Mixtec Shield underwent intense erosion and faulting, which caused changes in the upper courses of the Rivers Balsas, Lerma and Papaloapan.

During that geological process, which also involved high levels of volcanic activity, the rivers rising in the Sierra Mixteca carved out many deep canyons, further complicating the relief of the region.

Its inhabitants, who number some 200,000 [1] are predominantly indigenous, mostly belonging to the Mixtec people, who engage in subsistence agriculture.

The region lacks any major population centres and communications with the rest of the country are deficient.