Because there are racial-alike tensions within the Caucasian people, such as Nazi/Jews, West/Slavic, Protestant/Catholic.

Unable to reply to your other flagkilled comment, so I'll reply here.

It's amusing that bringing up facts in a community ostensibly self-selected to prize discovery and reason is sufficient cause to be silenced.

pg and the community he fostered has come a long way since this: http://www.paulgraham.com/say.html

Yes, that is absolutely correct. And I find it sad that such thoughtless mechanisms are exactly what powered the worst forms of racism in the history.

Edit: would just like to point out that I was flagkilled before any response came, so currently my post is invisible in this thread.

I don't know the history of it, but it seems likely that Greece waged a lot of war with the (slavic) countries north of it, so their slaves would be predominantly of slavic descent. Slavic people also have a pretty easily discernable look to them, at least many do, so it's not hard to imagine they could be subject to racial discrimination in Greece.

Lol how do you think 'slavs' got their name? Have you looked at the Arab and Ottoman slave trade?