If you are thinking of a Human in Equestria story, how much of human history would the main character reveal to the Equestrians? Or, if you took along a cube of nanotechnological entities, which when placed on the ground melts to form a wide disc. The disc becomes a map showing the world's continents and oceans with the North Pole at the centre. The map plays a film of human cultures, empires and states spreading across the continents. If a pony steps on any country on the map, a hologrammatic blurb of information rises to their eye-level. Now, the Equestrians are so peaceful, some of human history may startle or worse traumatise them, thus some of human history has to be censored.

5754333
What an oddly specific hypothetical question.

Equestria has had pretty bad conflict in its past — Discord, Sombra, etc. They're in a period of relative peace now, but they still seem to maintain something akin to an army. I'd let them have it uncensored.

5754336 Dear Cap'n Peter MacFarlane, are you really sure on that part?
Merely think of the Thirty Years War (1618-48), the Thirty-One Years War (1914-45), the mass murders of Hitler, Stalin, Mao and Saloth Sar; the Mongol Conquests, the Great Dying, the Atlantic Slave Trade, the Fall of Rome, the Fall of the Ming Dynasty, the An Lushan rebellion, the Taiping rebellion, the Napoleonic Wars etc.

In the Thirty Years War armies marched and counter-marched across what became Germany pillaging, looting, torturing, raping and killing innocent farmers and villagers as an unquestioned part of life. Some parts of the countryside were burned and barren until it waited silent for the Industrial Revolution to recover pre-War population numbers. The Religious Wars between Catholics and Protestants the previous century

In the Thirty-One Years War are the two World Wars, the Russian Civil War (about the same number of people died as in the whole of World War One), the Chinese Civil War, the Shoah (you know what it is), the afore-said dictators.

The Mongols killed so many people it is argued it spurred the Little Ice Age from the fallow farm-holdings growing wild, as well as the Kwarazam Shah in south-west Asia, and the Xi Xia in west China.

The Great Dying is the name for the fall by eighty per cent of Native American populations due to smallpox.

The trading of black Africans from Africa to the sugar plantations, on the boats, each had just enough space as it to be described as their coffin.

The An Lushan rebellion ended the light of the most culturally-enlightened (poetry, porcelain, art, writings) Imperial dynasties in Chinese history.

Similarly, the Taiping rebellion (the Kingdom of Heavenly Peace), shook and left the Qing dynasty stricken, It is possibly the bloodiest rebellion in human history, about 20 millions or more died.

King Leopold II of Belgium running the Congo as his personal property, his soldiers mutilating the indigenous people who resisted.

Violent racism, the fact hunter-gathering tribes fought each other every couple of years due to pressure on the land, etc.

Are you sure?

Sorry, this may be just a bit too descriptive. Anyway, let me know.

Mez Rex

5754333 I agree with Vital Spark. Although Equestria is mostly at peace now, it's clear that war is A Thing -- remember, the yaks almost declared war in "Party Pooped", and there's the Sombra war in the alternate S5 finale timeline. Add to that the fighting that occurred at the time of the Windigoes, the horrible reign of Discord and the threats posed by the likes of Tirek and Chrysalis, and so on. And that's just the stuff we know about. There was probably a lot more that's never been mentioned in canon. After all, no human being knows all of human history, either. Your long list is still only a fraction of everything that's ever happened, and equally what we've seen in MLP over six seasons, plus books, comics etc is only a fraction of everything that's ever happened in Equestria.

Because Equestria is a world where friendship is literally magic, I'm sure they'd find much of human history strange and disturbing. But that's not a good enough reason to censor it -- though you could write a great Alternate Universe fanfic in which Celestia did take that approach! (Which is the great thing about fanfic, of course: there is never just one way to approach it. )

5754616 I suppose before the Windigoes, you could say from time to time a brigade of reavers of one tribe could pounce on a village of another tribe and massacre every pony in the village and steal their food.
I also thought of the human main character showing Princess Celestia and Princess Luna hologrammatic-converted footage of the Trinity test - 1945.07.16 - or the detonation of the very first atomic device. To show them, and them only, the full power Humanity is capable of.
It's only Celestia and Luna, because if I include Twilight and Cadance; well, they could worry about this a species loosing this phenomenal power and tell Rainbow Dash, Fluttershy, Applejack, Rarity and Pinkie Pie, and Cadance would tell Shining Armour.
Well, I suppose you have differing opinions on Twilight and Cadance's reactions to the atomic bomb.

5754639
Do you intend the Big C to be worried, impressed or just not bothered by nukes? Depending on how you write her, C could easily be thinking 'firecrackers' (power of the sun, and all that...). I always treat her as 'weakly godlike', as she was in S1/S2 (same with Luna). In a very real sense, the Princesses are the ponies' strategic weapons.

Ponies don't need to fight ponies, not really. Their environment is dangerous enough (lots of aggressive megafauna).

Anyway, as to if you'd censor history -- you might, but mainly to show yourself in a better light. It all depends on the nature of the contact and what each party wants. The danger of censorship is what happens when the pones discover that the humans have actively hidden a chunk of what they are.

Personally, I wouldn't reveal too much about humans in general. While humans have accomplished extraordinary technological feats, they all have their drawbacks such as damage to the environment or the harmful radiation given off by nuclear waste.

Let Equestria and the surrounding lands evolve at their own pace and only intervene if absolutely necessary is what I'd say.