Tried asking this on the Reddit history pages, immediately removed for asking for a "basic fact", meanwhile sourcing is near impossible to find.
Ive been trying to find more sources on the origins of the racial identity construct, particularly in the development of widespread white supremacy, and how the "white" identity developed. In my research, it has seemed very clear that it developed in conjunction with the Catholic Church's rise to power at the continental scale. In this same location, fertile birthing grounds for settler-colonialism, capitalism, and white supremacy. Any recommended reading on the subject would be greatly appreciated.
Furthermore, as the title stated, I am looking for the earliest recorded instances of one peoples inflicting subhumanization behavior on another. Obviously conflict between different groups of people traces far back before recorded history, but I am very interested in finding when a group first identified as "pure" human, while declaring all those without said traits subhuman. I have a feeling there must be some Marxist text on this, so if anyone knows it I'd love to see it.
Selfish plug to the research I've done thus far if anyone wants to check it out
I would argue that any slave society has to necessarily view certain groups as subhuman, as it is an obvious moral fact that people who you see as equal to you should not be enslaved. The ancient Assyrian empire collapsed around 600 BCE, but at its high point they had tons of slaves and were known for being particularly harsh to their subjects. So, there are definitely examples of something like modern racism long before the start of Christianity.
IMO "whiteness" is just one example of hierarchy, and to a historian a few couple thousand years from now settler colonialism might not seem different than, for example, how the oppressive ancient Assyrian empire treated its subjects.