From a Texas point of view:
The exploiter divides the world into 2 kinds of people - us and them - then takes whatever the other has that the exploiter wants, justifying it because the other is "less than" the exploiter. A whole framework of myths gets built up to justify this. Stuff, land, resources - they're all fair game if the other is less human, and the ends justify the means. Once the exploiter gets what he is after, he can afford to appear and feel magnanimous and noble by doling out trinkets.
Is this a deliberate process? For some. Others are impressionable, or wanting to feel superior by right of birth, because deep down, they know they're not.They invest in the mythos. And the lies and attitudes get passed down through the generations.
This communal belief system is partly sustained by shame and denial. (How can we possibly be descended from such barbarians? It isn't true! We're good people! Maybe they weren't so bad.) Can you bear the burden of the sins of your fathers? Imagine growing up believing slavery was evil, tracing your lineage back, and coming face to face to face with an ancestor who owned slaves. Theory becomes an uncomfortable reality. Like New Yorkers discovering a slave cemetery in their midst. (It happened.)
On the other side, being a victim or descended from victims can become part of a person's identity. It also sets the person apart. It's perverse, but it happens.
Can a white person ever understand what it is to be of another race? Tell me, can a straight person ever understand how it feels to be called a fag?