Where is the Sierra Madre del Sur located in Mexico?

The Sierra Madre del Sur is located in southern Mexico as part of the Southern Highlands region.1

Its geographic position is defined by the following features:
* Southwest: It is outlined by a narrow, discontinuous coastal plain along the Pacific Ocean, extending approximately from Puerto Vallarta to the Gulf of Tehuantepec.21
* North: It is bounded by the structural depression of the Balsas River.2
* East: The region terminates abruptly at a magnificent escarpment that overlooks the Isthmus of Tehuantepec.2

These crystalline mountains reach elevations of 7,000 to 8,000 feet (2,100 to 2,400 metres) and often meet the sea to form a rugged coastal margin.1