This painting is oil, old and I've been searching for the location. It would help if this mountain range could be sourced, I could then figure out who the artist might be.
This painting can be found online (and a friend of mine did) and here is a link.
That site mentions the picture to be by an unknown artist but the title to the picture: "Herbst Am Silsersee".
Herbst means autumn (or fall,) Silsersee translates to Lake Sils, and that has a Wikipedia page. And that lake is located in Switzerland and that makes it the Alps rather than the Rockies.