https://en.wikipedia.org/wiki/Lilliput_and_Blefuscu
> The novel further describes an intra-Lilliputian quarrel over the practice of breaking eggs. Traditionally, Lilliputians broke boiled eggs on the larger end; a few generations ago, an Emperor of Lilliput, the Present Emperor's great-grandfather, had decreed that all eggs be broken on the smaller end after his son cut himself breaking the egg on the larger end. The differences between Big-Endians (those who broke their eggs at the larger end) and Little-Endians had given rise to "six rebellions ... wherein one Emperor lost his life, and another his crown".
So let's work towards squashing racism every time it crops up. We had a Catholic president, remember when that was a huge deal? Now nobody would bat an eye. Let's continue this for women, POC, LGBT, and so on.
It's an ongoing battle.
The Rwandan genocide was Hutus killing Tutsis, yet the distinction between the two was very arbitrary and in a lot of cases boiled down to "the Belgians liked your ancestors more so declared you to be Tutsis".
Nazi Germany was allied with Japan despite all their racial purity rhetoric and some Jews were designated as "honorary Aryans". White supremacists today will gladly talk about the portion of white people who are "race traitors" and deserve to die.
Humans might have a natural tendency to favor those in their "own group", but exactly what that means is completely arbitrary.