It's because of their geography (woot, history >.>). And we're not really sure 'where they come from' but if we're going to look at the geography, they don't exactly work under the sun. Like the Karayans, they're notable for their dark skin, mentioned too in the S3 manga (and probably in S3 game, but I never played it). They've been living in the Grasslands and hunting. For all we know--since the beginning and that would be a long time already, generation to generation.
Yes, there are hunters existing too like Kinnison and Jacques but are white. Be reasonable; skin colors are because of genetics and its hereditary >.> if you must know, the body will use more melanin to darken the body to protect it against the vicious rays of the sun when exposed to them for a long time--generations then passed down...
Yea. But we don't know th exact geography of Suikoden, but I pointed it out and used the Karayans as example.
It has nothing to do with racism.
And yea, I did assume they were Japanese >.>