They were discovered in 1876 I believe. I think at the moment there are around 300 or so in the herds. Unfortunately they round a large amount of them up every few years and few get sold, most of them go on a one way trip. Which I find absurd. They claim it is to "save the unique plants" and so on. But they're also living on a large area where the army train, I think thats the underlying reason they get rounded up.
They are beautiful really, yeah It does look like she has a bit of Arab in there! in that photo. She was originally wild, round up and (thankgoodness) sold.