Doulos:
The people that were not a part of the group were until suddenly someone decided they were not. That's why you read horrific stories of people who were neighbours for years and years suddenly turning a blind eye, or even shouting encouragement, as their Jewish neighbours were dragged off to camps.
In America you have Japanese internment camps setup when most of those folks did absolutely nothing wrong and were good friends and neighbours that one day just became the enemy.
I agree that only outsiders become the object of wrath in these situations but when the definition of who an outsider is changes on a regular basis then I don't see how that's really helpful in determining any set of values or behaviours as being 'set' in any way.
As for Gengis Khan and his people, that's almost impossible to answer. Again, the definition of who was part of "his group" was very fluid. He killed his own brother (can't remember why - stealing food I believe). If you did everything he wanted the you were a part of his group, but if not then he would likely attack, rape, kill and destroy everyone in your city. So, again, of what value is that to determining morality?
Your statements show a failure to understand the situation, or the motives of the people involved.
Untill after World War Two racism was so ingrained in most of the world that no one even noticed it, including Anti-Semitism. The cristian Germans already hated their jewish neighbors, or at least in most cases were not close friends with them due to social pressure, and the few that did oppose what the Nazi's did suffered the same fate.
In America it was much the same with the (please note I use the following term only to illustrate my point.) "Japs", their facial features and customs set them appart from the "white" majority and they thus were seen as an 'other' and therefore dangerous. No, what was done was not right, but it was consistent with the precedent Kitsara is stateing.
In fact America is very unusual in how much it has become oposed to racism and classism.
Take for example most Native American languages: their word for themselves corectly translates to "people" as in 'we are people, everyone else are not real people'.
It is worse with some other cultures: Do you know what the word for foreigner in Japanese actually means?
Gaijin: Adjective; Forign
Thing.
Not foreigner, foreign thing, in there eyes not only are we not people but we are not properly alive.
The concept of a "Human Race" is only a few centuries old, and has still not gained cultural acceptance in many places, any mark or difference can be enough to spark murder or on a larger scale genocide. But within the culture, with those who are accepted as part of the "us" group: a basic standard of behavior is applied.
As to Gingis Khan and his brother: Stealing food was incredibly serious, the mongols lived in constant danger of starving so stealing food runs up against all five universal rules, directly or at one remove at most. I don't know enough about the case to know how his brother died: crime of passion, trial and execution, or what, but many many people have been "lawfuly" hanged for exactly that crime.