You know, Frettzo... -sigh- I don't want to bring this up, but maybe I have to. 

I know this is Equestria and all, but there are some very unfortunate implications involved in that origin story. Um, the zebras (being equines that live in Africa) have an African-influenced culture. African people have dark skin. In your story, it's the [i]black[/i] brother who is unkempt, dirty and vengeful, envious of Khem (who has a clean, soft [i]white[/i] coat). Kellah sends a black mare, who falls in love with Khem, and of their offspring, quote, "the whitest of them would rise to the task of leading Khem's people".

White=good, black=bad. :( I don't like it, Frettzo. I really don't.

EDIT: I know this isn't what you intended, but it's very easy to get that out of it, especially considering that they're [i]zebras[/i].

EDIT 2: In an Equestrian zebra origin story, what I expected more than anything was two different tribes, one with black coats and one with white coats, coming together in harmony after some kind of disaster. They thought they were enemies, but when the time came, each tribe came to the other's aid. Thus, a new tribe was formed, both black and white, and that's who the zebras are descended from. I mean, sure, it could do with a lot more fluff than that, but off the top of my head, that's the basic story I would have gone with. The whole white brother/black brother thing just does not compute.

I think it's cool that you put the effort into coming up with a legend for the dawn of the zebras, I really do, but the implications are overwhelming to me.