[In America, you find that this description is complete and utter humbug. We can live without Latinos killing Black People killing East Asians killing South Asians killing Arabs killing White people.]

A few things.

1. I mentioned cultures and beliefs, and I specifically and intentionally left out race. You are just trying to bait me here.
2. In the United States, the dominant culture is General American culture, derived from Anglo-Saxon culture with minor German influences although the political and demographic influence of Mexican and Central American culture is now growing.
3. In many parts of the United States, African-American subculture now differs enough from General American Culture to warrant riots between different communities. Their interests, values and beliefs have grown too far apart now, and they feel like they no longer owe allegiance to the United States or to the existing authorities.
4. The irony is that the United States has a history full of what I described here. First came the various Native American tribes, who had a habit of pushing each other around, expelling each other from prime hunting grounds and kicking each other to the ground every now and again. Then came the first Europeans, and generally they weren't too kind to the natives. Then came more Europeans, and before they could count to ten the Europeans were fighting each other. The Native Americans were pushed further and further west as European groups - who eventually united as one language and culture pushed out all other cultures and became dominant in the state - went for more and more prime hunting grounds and farming land.

[Nationes Pii Redivivi wrote:
If they are fighting, I don't think it is because they inherently hate each other and want to kill each other, unless you are projecting yourself onto others.]

I doubt it. I think this applies to every place in the world at any time in history. There's an interesting field of study in archaeology that's based around figuring out how and when cultures supplanted and replaced each other based just on their pottery and their burials. This has been going on for literally tens of thousands of years, and it's typical human folly to think that it'll magically stop because "we're civilized now". It's not that people hate each other, it's that they're rivals, and eventually any culture that exists in an area will come to believe that the land is theirs. In the United States, you could say that, whenever you hear people in places like Ferguson speak of 'the community', you also hear them speak of the authorities and the rest of the United States as outsiders.

Finally, here's a nice song.
https://www.youtube.com/watch?v=-evIyrrjTTY