All small tribes throughout all of history fought wars the same way and for the same reasons. Money and women. They attacked any other tribe, killed or enslaved the men, and took the women and girls. All Indians did this, Vikings did this, Japanese, Chinese, and niggers in Africa still do this today.
To the victor of war go the spoils, since forever. Might does in fact make right, to think otherwise will only eventually get you killed. You can't morally shame someone who breaks into your house and steals everything into not doing that.
Laurese Van Der Post illustrated this perfectly writing about the African Bushman.