Basically it derives from the same origins. There are certain laws of ethnic relations in history of humankind, such as:
1. law of percentage: lets say a black person somewhere in gothenburg or copenhagen would trigger an amused curiosity and the outpouring of sincere sympathy, however, if you "inject" immigrant workers up to the fateful threshold of 4-8 percent and you will already have a racial situation - the nature of social relationships changes, engendering ethnic tensions, global reflexes painful to describe. The more the percentage increases, the more class struggle transforms itself into racial confrontation. Basically, this percentage is sufficient to make racial discrimination appear spontaneously in people who previously believed itself wholesome and devoid of any racist sentiment.
2. The law of assimilability: If majority and the minority belong to the same large ethnic group (all are white, or all a asian), then assimilation occurs progressively. For example, Spanish or Portuguese workers despised in France not so long ago, integrated themselves into population within the space of one generation; same for descendants of corsicans and the poles during napoleonic era, same for bambara minority living in senegal. But if the ethnic and cultural gap is too big, tensions are exacerbated with time. Like African Blacks and Arabs find themselves in this situation in Europe. Coexistance basically becomes possible only in a truly Socialist state or a state that has adopted a high morality philosophy.
3. the law of distance: like two ethnic groups that are not fighting over the same living space or same market and occupy different territories separated by space can enter into normal relationships. Like that an alliance can be explained during world war 2 between hitlers germany and japan. or relationship of pretoria with israel state.
4. the law of phenotype: basically physical appearance. It would matter little tgat botha and zulu in africa have the same genotype (same genes in the chromosomes) and it would have no influence on their daily lives because their external features are so different.
Laws of class struggle according to history applies only to societies previously made homogeneous by violence. Funny, that the most modern nations actually went through this bestial struggles before (Americas, australia, new zealand, good part of asia, greenland, huge part of pacific, scandinavia, etc, etc).For example Blacks of Americas were brough over to work the land, while the indigenous races were being destroyed. So, the "more advanced" barbarious conquerors exterminated/drove out whole populations, devastated or abandoned productive forces they they simply did not know how to use. This specific law is one of my favourite... how spartan domination ended by crumbling particularly because of the great numeric weakness of their REAL citizens. Because their society consisting of spartan conquerors and lowly helots both belonged to the same large white-skinned 'race', ethnic differences became blurred and it allowed class differences appeared only in an economic sense.
Same goes for Rome and Carthage, Rwanda-Burundi, Francs and Gallo-Romans.
Have a look at the american immigration laws and how it progressed throghout 19-20 centuries. This law also gave birth to so called intra-european racism, etc.
We forget that the passage from a clan to a monolingual tribe and to ethnic group and to nationality historically was a result, a consequences of clans exogamy. It is still widely discussed by specialists. But it marked starting point of the current civilization.
Endogamy was prohibited and we, humans, just started fucking people from the outside kkk several neibourhing clans contracted marriage ties that led them eventually to speak same languages despite that their original idioms were different.
The number of clans to gather together to work a more or less powerful tribe didnt follow any rules and depended mostly on the fertility and extent of the lands occupied by the group. Thus was born nationality.
In the course of history, when two groups of people argued over a vital economic space, the slightest ethnic difference can be magnified, temporarily serving as a pretext for social and political cleavage: differences in physical appearances, colour of your passport, language, religions, morals and customs.
We forget that basically future generations must forget about the dead so that the conquering people can undergo a rebirth with an angelic consience.
Why do we almost idolise, for example, conquistadors, holy crusaders and vikings? Pillagers, rapists, murderers and worse.
Most of the things we learn and follow, most of the times, blindly, things we consider as truths and solid facts, the very foundation of our personal universes - it was predominantly build based on someones ideologies.
Books, that our kids and us read, are also written under certain circumstances, conditions, requirements, with certain motivations. Dictated by an ideology.
Sooo.... sorry for the massive message. It just questions like this trigger something inside me, something that i consciously try to understand and overcome. For before we are races or nationalities, boys or girls, gays or straight, we are humans.