So much awful history, so much of it buried.

Saw this movie when it came out because I had read the book by Adam Hochschild about 20 years ago:

It is the Eurocentric idea of conquest and claiming resources. We were founded on those principles and carried on the tradition.

Millions killed by colonialism on every continent except Antarctica.
Native Americans
Aboriginals in Australia.
The Armenians.
Hell even the Lebensborn which were the "Aryan" children of Nazi SS members were institutionalized after WWII where they suffered abuse and neglect at a criminal level because of their relationship to Nazis and due to no fault of their own.
[en.wikipedia.org]
They're all dead now.
No accurate number can be posted for Native Americans that died at the hands of white settlers starting with the Spanish around 1500 on through the French that taught them to "scalp" their enemies and then the English which gave them diseased supplies in an effort to exterminate them.
Sometimes it's a bit much to take in, the magnitude of human misrule over humans.

The first time I heard the poem "The Stolen Child" by William Butler Yeats it brought me to tears.

Where dips the rocky highland
Of Sleuth Wood in the lake,
There lies a leafy island
Where flapping herons wake
The drowsy water rats;
There we've hid our faery vats,
Full of berries
And of reddest stolen cherries.
Come away, O human child!
To the waters and the wild
With a faery, hand in hand.
For the world's more full of weeping than you can understand.
Where the wave of moonlight glosses
The dim grey sands with light,
Far off by furthest Rosses
We footed all the night,
Weaving olden dances
Mingling hands and mingling glances
Till the moon has taken flight;
To and fro we leap
And chase the frothy bubbles,
While the world is full of troubles
And is anxious in its sleep.
Come away, O human child!
To the waters and the wild
With a faery, hand in hand,
For the world's more full of weeping than you can understand.
Where the wandering water gushes
From the hills above Glen-Car,
In pools among the rushes
That scarce could bathe a star,
We seek for slumbering trout
And whispering in their ears
Give them unquiet dreams;
Leaning softly out
From ferns that drop their tears
Over the young streams.
Come away, O human child!
To the waters and the wild
With a faery, hand in hand,
For the world's more full of weeping than you can understand.
Away with us he's going,
The solemn-eyed:
He'll hear no more the lowing
Of the calves on the warm hillside
Or the kettle on the hob
Sing peace into his breast,
Or see the brown mice bob
Round and round the oatmeal chest.
For he comes, the human child,
To the waters and the wild
With a faery, hand in hand,
For the world’s more full of weeping than he can understand.

Most people were never taught about most of the atrocities that have been committed worldwide.

Most of Europe screwed over Africa and the Mideast. There are still lasting effects; one of the worst was the way the Europeans cut up countries and their tribal populations so as to put the minorities (by tribal peoples or religion) in charge, which then continued the violence began by the colonizers.