There are people today who bear the physical characteristics and/or undeniable cultural affiliation to groups that have a history of being undermined, overthrown, persecuted, enslaved, or murdered by the hundreds of thousands or millions.
They may be identified by their religion or the color of their skin. Their oppressors typically embellish those characteristics with primitive behaviors, lack of intelligence, literacy or other behavior deviant from the oppressor's own expectations of "civilized behavior."
The volume of historical propaganda against the oppressed is eternal and now searchable online as "legitimate history," the clarion call of which is "he who forgets history is doomed to repeat it."
The first time you learn the history of some of your classmates, you ask yourself "why were they treated that way?"
Then, you tell yourself "I wasn't treated like that so I must be better than them."
Then you gather with those like yourself and talk about them.
Feeling confident in your group, you begin to mock them.