Comment by nunobrito

You are imprinting your worldview on someting that differs from historical facts, maybe influenced by anglophone chronicles of what the spanish did in the americas. Spanish were no angels, however, much of what is published tends to be biased and differ quite a bit from what happened on the ground.

Despite neighbour to Spain: Portugal built a different culture altogether since its inception as an iberian kingdom. For example, instead of wiping out the muslim populations, the first king established a policy nowadays known as "don't ask, don't tell" in regards to religion. Which clashed with the Spanish/Italian approaches but at the same time permitted rapid expansion of territory since the population was absorved rather than decimated.

The Brazilian land has dense vegetation and native populations that never generated large settlements nor advanced cultures as you'd see in other parts of America, existing in a continuous state of tribal warring against each other.

The crown/church forbid portuguese women from travelling overseas and the number of sailors travelling was low (the kingdom was small population-wise). Portuguese technology and culture were very, very, very attractive to the native populations who came in contact with these sailor crews. They quickly mixed with the locals to create blood-related families on those locations with local leaders (same as done in India). The portuguese doctrine remained the same as during foundation times of the kingdom, aimed to mix as much as possible with local populations to thrive. This resulted in centuries of family ties across the atlantic that still last until today. Looking on my own example, I keep family ties on three different continents that all speak the same language.

All of this to say that integration was very fast from the native population point of view to join the empire because of mutual benefits for either parties, to the point that the portuguese army in the Americas was composed and lead in majority by natives themselves which went to subjugate rival tribes with better equipment than the counterparts.