Big Bend National Park was established for us all to enjoy, it was home for others. People lived their lives in the region...the earliest settlers were Mexicans establishing residence in the early 1800s. The park's website has a page on those original settlers here, as well as an entire section on stories about residents of the area.
Another place you can learn about the people of the region is Alpine's Museum of the Big Bend on the campus of Sul Ross State University. Plan to stop by on your visit to the area!