Movie submitted by Brian Lee:
I have a vague memory of a film seen years ago, at night. It’s about a white man who, in present time, discovers an Indian tribe living in a hidden valley that tries to avoid any external contacts with the white men. The protagonist rides and horse and has a dog that is hit by an arrow. Years before, an Indian child was found along the railway and the news was reported by newspapers. He noticed the newspapers in a library. In one scene there is a plane that drops white pieces of paper in the sky while the protagonist is speaking with a wise old man. The warriors of the tribe are called the dog-men.