Horseback Mountain

When I was exploring the 'cowboyness' of Brokeback Mountain, I had only watched the trailers and read some things about it on the Net. (Caveat: my ladyfriend had seen it, and liked it.)
But an interview with the screenwriters showed more of the movie than I'd been willing to pay to see, and I think they proved my point:

The boys of Brokeback Mountain herd sheep.

Okay, so they do it from horseback. That doesn't make them cowboys. Cowboys herd cattle. Sheepherders herd sheep. That's the Rule of the West.
And, in more than one Western, the cowboys hate the sheepherders.
Maybe McMurtry wrote a script about a far more classic theme than I suspected...