is it not just our bias? Human nature is the same. Germanic Racism produced recently large bad results (euthanasia, nazism, etc) and many literature and media, pro and against, it even had philosophical interactions and a body of pseudo-science (e.g determining people worth from cranial measurements) or even occultism.

It is easy to find openly racist sources to study it, close to us in Europe and USA and in recent centuries. Other racisms did not had such large recent consequences, and documents about them are not as easily accessible, abundant, or in the right languages. I upvoted the answer about Tacitus above: but if no racism had happened recently, it would be just a curious historical citation.

Think how people think that western slavery of blacks was the largest, baddest, and longest one, when Arab slavery of both blacks and whites was larger in numbers and duration.

Another take is to consider that other racisms may never had the opportunity to show how bad they are in the same scale. Given that western civilization has been dominant in the last centuries, the first dominance that may be called global, its racism is the one that had more opportunities to develop. The simple idea that a strong man turned bad does more harm than a weak bad man.

Suppose that China takes over the world (not as easy as some believe, they have lots of internal problems too). Given what they are doing in Africa (look for 'Chinese debt trap'), and supposing (be pessimistic as a thought exercise) that a very racist mentality develops on a Chinese dominated world, how much harm could they do? No people is above racist tendencies, China means "middle kingdom', in the sense that in the borders are tributaries or barbarians (in the same way as Greeks called all others barbarians), and communism itself tends to not respect of individual rights too.

The same reasoning could be applied to any civilization. Suppose they dominate the world, and exaggerate their racist tendencies.

Some Muslims complain that the Arabs see themselves as special Muslims, as the religion has obvious Arab roots. Affirmative action may be viewed as racist or as a racism generator. Bantu expansion in Africa was hostile to non-Bantu peoples (some call it the longest genocide in history). Hindu religion does not allow them to go out of India. Hindu legends tell about the barbaric dark-skinned peoples from East India attacking the civilized, lighter-skinned people of the West India Aryan Kingdoms. The Japanese were not above racist behavior during their occupation of China or Asia. Many languages have xenophobic or self-centered words, e.g., the Tupi (brazilian indians) word for their own language means "beautiful language".

But why would we care for such things, distant in time and/or space, and/or with lesser consequences? At least, even if you care, they would be much more difficult to find or study than our usual racism.

What would be really different is a racist people convinced that they are NOT the superior people. A noble Frenchman could easily argue that his noble class is the finest example of Frankish purity ruling over the mob of mixed Franks, Gauls, Celts, and romanized peoples - which as whites would be not so far below anyway.

And about Brazil: the other answers are good, but also note that they did not need to promote immigration from Portugal and southern Italy - they already had many coming, both private individuals and from larger schemes, for plantations and even industry. Immigration from Spain to Brazil never was a god bet: why would not them go to Spanish speaking America instead? In my Italian family the elders tell of people that deserted their immigration scheme from Italy to Brazil to go to Argentina. From Spain this problem would be much larger. Besides that, germans and northern italians had generally higher levels of education, better hopes for agricultural productivity.

In that period of history Germanic people were relatively superior compared to others

18th and 19th century were interesting periods, because for the first time in history rapid and systematic technical progress started changing lives of humans across the globe. Yes, there were inventions before, but as a rule they were sporadic and haphazard, rarely revolutionary changing established traditions. But now, with systematic scientific approach, new era of Enlightenment and industrial revolution, time has come for birth of modern anthropology. One of the questions for this young scientific branch was do various human races (subspecies in modern language) differ and how much ? Does this difference affects their level of development ? It is indisputable fact that in that period European powers (and people of European origin in United States) dominated world stage. Ottomans were in decline, China was dormant, Japan started modernization in latter part of 19th century and again on European model, India was being colonized, Africa even more so, countries of Latin America were struggling for independence etc ... Therefore, it was easy to conclude that among all human races European Whites were most developed, and therefore most worthy. But even among Whites distinctions could be made to select most productive part.

Let's now examine various European countries: Great Britain was becoming leading world power, and much of it was based on their technical, scientific and cultural advantage. Britain was considered to be Anglo-Saxon, part of the heritage was Norman, again with ties to Scandinavia and Vikings. Nobility of United Kingdom had blood relations with German noble houses on continent (for example with Saxe-Coburg and Gotha) . There was also Celtic part of British culture (especially in Ireland and Scottish highlands) but it was considered to be inferior and relatively primitive. Irish especially were deemed to be lazy, dumb and non-industrial. Therefore, Britain and latter also United States (which beside British had many inhabitants with direct German or Dutch ancestry) were clear examples for Germanic dominance. Next we have Scandinavian countries (mostly Sweden at this time) , various German states and Habsburg Monarchy (Austria) on the continent . German connection is obvious here, with especially significant accomplishments in philosophy, science and musical arts. What is worth mentioning is the fact that Austria had large Slavic population under its control, seemingly proving the point that Germanic nations are born rulers (master race). Even Russia served to prove this point : although large Slavic empire, its ruling class, from Romanov dynasty to various German nobles coming to Russia to serve as military leaders (one example would be general von Bennigsen), had lots of German blood.

What about France, Italy and Spain ? These were so called Romance peoples and were used as examples of both strength and weakness, or to prove the point that mixing with lesser races would eventually weaken great culture . Spanish used the term Blue Blood (Sangre Azul) to detonate pure blood nobility with roots coming from Visigoths and not mixing with invading Moors(Arabs). These were deemed to have Germanic roots and fit to rule, and they were the ones that created Spanish empire. However, unwashed masses did not have so pure blood, they were intermixed with Moors and later with American Indians in colonized Latin America. According to racial theories, this diluted the quality of population leading to eventual decline of Spain. Similar thing happened to Italians, with North being more industrial and cultural, with South falling behind and dragging Italy down (curiously, remnants of this idea still linger in Italy today, with political parties like Lega Nord even going so far to seek independence). Finally in France, Frankish culture was considered as dominant (hence the name of the country) and most worthy - southern parts (Provence for example) that were under influence of Mediterranean culture were considered to be less developed and less worthy.

With theory now constructed around Germanic peoples, question now remained : where could we find purest examples of this race ? Answer was easy enough : remote parts of Scandinavia, isolated enough to preserve this mythical purity of blood . It didn't matter much that these "pure lands" were relatively undeveloped and primitive compared to great European cities. Racial purity now became value on its own, as a logical conclusion of racial superiority theory.

To German supremacists, the Norman conquest of England provided a template for a successful invasion, after which the invading tribe would for centuries rule over conquered people. It is well documented that the aristocracy and the king were still using French until the end of the 15th century.

This was also true, at least to some extent for all nations that emerged after the fall of the Roman Empire. Gauls were conquered by Franks, Spaniards by Visigoths, Britons by Anglo-Saxons and then French-speaking Germans, Latins by Ostrogoths forming local aristocracy. Therefore German historians during the 18th century could claim that for centuries Germans were the ruling class; blue blood meant German blood. Through intermarriage with conquered people, the aristocracy eventually lost the "German looks".

In addition Germans claimed that the ancient Indus civilization was created by Aryans (Germans), who migrated from Europe thousands of years ago.

This kind of view can be attractive not only to Germans, but also to European aristocracy, which claimed that their ancestors were German tribes that conquered Roman Empire.

(Based on this theory of conquest, some English racists also claimed that William Shakespeare was a German.)

I blame Tacitus

In his text Germania (published circa 98 AD) Tacitus gives a lengthy description of Germany and German tribes. While he does not describe them as "superior" -- in places he seems to use them as a foil to contrast supposed German virtues with what he sees as the flaws of the Roman character (adultery vs marital fidelity for example).

And in particular as regards to racism he describes them as particularly "pure":

For myself, I accept the view that the peoples of Germany have never contaminated themselves by intermarriage with foreigners but remain of pure blood, distinct and unlike any other nation. One result of this is that their physical characteristics, in so far as one can generalize about such a large population, are always the same: fierce-looking blue eyes, reddish hair, and big frames - which, however, can exert their strength only by means of violent effort. They are less able to endure toil or fatiguing tasks and cannot bear thirst or heat, though their climate has inured them to cold spells and the poverty of their soil to hunger.

Surely there are other factors, and it is extraordinary that it should persist but I believe it starts way back with Tacitus.