Sweetgrass (2009)

Sweetgrass is a 2009 documentary film that follows modern-day shepherds as they lead their flocks of sheep up into Montana's Absaroka-Beartooth mountains for summer pasture. It was directed by Lucien Castaing-Taylor, a Harvard anthropologist, and produced by his wife Ilisa Barbash. The title derives from Sweet Grass County, one of several in which the film was shot.

More at Wikipedia.