I think it's just white hair from scarring. If you look at the big bay behind the people, he's also got it, and in exactly the same places. They don't use much padding under the saddles and they're pretty basic, so I suspect they're marks from poor-fitting tack.
I'm only here for a few weeks and pretty busy with work, so I haven't managed to wangle any riding time yet. I'm still working on the idea, but I'm not sure it'll pan out. Plus I'm a girl, so it's not the most obvious thing to arrange. I speak minimal Dari - as in, I can greet people and ask where/how things are - but I'm afraid otherwise I have to work with translators.
The Iranians have some pretty nice horses too, from what I remember. My sister-in-law is Iranian and I learned some Farsi when she and my brother got married, but I've forgotten it all now.
Four horses, two people. 4000km in to the South American leg of our trip,and now in Brazil. Drop us a line on The Great Horse Trip