The Mexican Major Frederick Remington (1861-1909)

The picture has something of this: cavalry, people, seated, mammal, man, group, military, equestrian, group together, cowman, lid, rider, many, veil, transportation system, horse, race, soldier, weapon.
Perhaps it’s a painting of a man riding on the back of a brown horse in front of a group of men on horseback in a desert area with mountains in the background.