Sierra Madre Oriental. These rugged mountains of the eastern portion of Mexico are steep and difficult.
Spanning 1,000 kilometres (620 mi) the Sierra Madre Oriental runs from the Rio Grande on the border between Coahuila and Texas south into central Mexico.
Mexico's Gulf Coastal Plain lies to the east of the range, between the mountains and the Gulf of Mexico coast. The Mexican Plateau, which averages 1,100 metres (3,600 ft) in elevation, lies between the Sierra Madre Oriental and the Sierra Madre Occidental further west.
The climate of the Sierra Madre Oriental is drier than the rainforest areas further south.