In the Chihuahua region, Mexico, there is a tribe called Tarahumara or Raramuri. It means “runners on foot” or “those who run fast” in their native language.
Documents show that there are only less than 70,000 Raramuris. I encounter about them when I read Born To Run. They were featured there. They are famous to run long distance because of the rough canyons which they live. 100miles running is no sweat for them.
Long distance running is essentially for communication and intervillage transportation.
More on Raramuri from The Lonely Planet.