It's hard not to be cynical in this world.
And you think everyone before western colonization was enlightened and multicultural? Sure their political regions were more complex, but in-groups and out-groups have existed in every region since at least the dawn of civilization, and those in-groups were typically defined by a range of factors including but not limited to culture, language, ancestry (and by extension, ethnicity), and religion.
You must have been sleeping through World History class if you think everything was kumbaya all around the world until the Europeans showed up...
edit to add:
I'm sure we all want the world to be such that everyone can just get along and coexist with each other, but that's simply not the world we live in. And seeking simple solutions to complex problems is never helpful. Pretending everything would be perfect if it weren't for those pesky Europeans is reductive. You can scream "blame white people" till you're blue in the face, but ultimately you're just playing into the same racialized dichotomy that you feign to be criticizing.
After all, it was always just a sliver of white people even within European societies which were the dominate classes there, who oppressed everyone they could, including the rest of the white people they shared a nationality with. The vast majority have always been disenfranchised, just like everyone else. And everyone else had their aristocracies too. Let's not pretend that's an exclusively European thing.