There are many organizations, associations, and groups. Political parties, ideological groups, sports organizations, and so on. It could be race, ethnicity, nationality, religion, social class, company, place of residence - town or village, etc. Anyway, people belong to various places.
And they are attached to the places to which they belong. It's natural, but it's also an easy target for tyrants.
He tries to convince people that "only" his "faction" is important and should be protected.
If you think it is the "only" one, you will lose respect for the others. Indifference, or worse. It is the beginning of hatred, harassment, and violence. You have fallen into the tyrant's trap.
And tyrants love to make up, more than anything else.