He was actually a person from the history of Joshua Tree, now a national park in the SoCal desert, but back in the time when I spent a lot of time there it was a national monument.
Lang was one of those drifters around whom legends grew back in the days of the old west. I spent a lot of time in Joshua Tree back in the 60s, as a child, and his grave was still there along a road in the park back then. He was involved, the details are murky, with the Lost Horse Mine in the park back in the old days. It's a long and interesting story, but the upshot is that he ended up wandering around the desert trying to recover from his loss of the mine, and finally died of exposure by the road. His grave was supposedly where his body was found. Over the years it was vandalized and perhaps even robbed, and my understanding is that it is no longer marked or maintained.
Joshua Tree was also the site of the Keys Ranch; in fact, the park was partially comprised of land that was appropriated from the ranch, and when I was there in the 60s, there was still a lot of fencing there that had signs like "Private Property! Keys Ranch, Keep Out!". I'm sure all of that is gone now.
One more interesting factoid: old man Keyes was once prosecuted for murder. He was acquitted, and his lawyer was none other than Earle Stanley Gardner. Gardner was the author of the "Perry Mason" novels, which begat the TV series, and at one time was considered to be the most prolific novelist in the world.
Yes, I have some personality problems...
Tell us more, Death Valley Alfy.