Diplomacy- Why does it have this issue?

Hey all, I just finished my first full game of Brave New World. I played on Warlord because I wanted to get to know all of the new features without worrying about interference. I played as Mongolia on Standard speed on the Continents map.

I made only one city, rushed GL, then rushed NC. After that I got the luxury techs I needed and beelined to Chivalry. Soon after I had 9 Keshiks, a Khan, a Horseman, Swordsman, and Pikeman. I swept around the continent, killing the three other civs that existed with me, which were Rome, Germany, and Korea. I kept the cities on luxes I didn't have and razed the useless ones. I didn't kill any city states, instead allying with them (via barbs and resource connection domino effect) for the happiness to maintain this empire that seemingly appeared out of nowhere. Meanwhile, after I got chivalry I beelined to Astronomy so that I could discover the other civs asap and be the starter of the World Congress. This happened, and I was pleased with myself.

Then it happened.

Every civ hated me for every war related reason.

How could they know? As I was traveling there with my Caravel the Science pop up appeared and said that I was the most advanced out of any civ. There was no way they could have contacted one of the now extinct empires. How did they know that I waged war so much? For the entire game they hated me, with the most positive relations being Hiawatha/Neutral, Ramesses II/Guarded, Askia/Guarded, Ahmad al-Mansur/Hostile. Why is this? It put a damper on my game, knowing that despite the free luxes I gave them and many concessions that I would never be friendly.

The rest of the game went well. I prioritized religion (Catholicism) early, with the benefit relevant to this post Itinerant Preachers. I spread it quickly on the other continent when I finally put one city there. I took an adjacent city state on their continent for a better foothold. With me having early control of the Congress, I put through every vote in my favor. Morocco was tied with me. I used my vote power to embargo him from every civ, and the next vote was to embargo trade with city states. He had a huge army, as did I. I put through the Standing Army Tax to cripple him further. Soon every AI was making negative money. Between having every money building and Tithe in my religion, which enveloped my personal continent and about 1/3 of their continent I was still making about 500 gpt. I bought all of the city states favor and there was not a damn thing they could do about it (I have newfound respect for Patronage). I purposely held back on conquest and science victory so that I could experience the full power of the World Congress and spread my culture. I had influenced Songhai and everybody else was close. Hiawatha even had a revolution where his order switched to my freedom via my tourism. I won diplomatic victory. In the end the UN had a total of 59 delegates, and 40 of them were mine

I think I might start playing on Epic just so these tourism and voting features seem more important to the civs in the game.

TL;DR -> I really love the new features of BNW, especially the World Congress/United Nations. I don't love the psychic AI though.

It's not "historically realistic", but it is "gameplay realistic". It levels the field. Why? Simple. When you as a human player finally reach the "other" continent around mid game, and find one huge civilization sitting there, perhaps with small remnants of other two, and look at the names of the cities of the mega civ, you immediately know if the civ built them itself or if they were conquered. If the latter, you immediately flag that civ as a danger (a warmonger) to your plans, and immediately start planning their demise, and perhaps the "liberation" of some of those cities...

The AI needs something similar to level the field. You were indeed a warmonger, and cannot pretend to get away with it only because the AI cannot understand origins of cities from reading their names (or perhaps the code does just that, I don't know, de facto mimicking what we do). Either way, it's just fair. The opposite would be just to easy for us human players, and break the game midway.

How is it not historically realistic? Did you completely eradicate every trace of these conquered civilizations and swear every single one of your millions of citizens to secrecy? Of course not. Merchant ships from Mongolia arrive on the other continent, some ethnic Korean and German crewmen (or maybe refugees) tell the story of how Mongolia came to control an entire continent, voilà, everybody is suspicious that you'll come over and try to conquer them too.

After I made the original continent the Official Empire of Mongolia I just wanted to hold hands and be friends with everybody else, but I guess you can't do that... Does the whole thing where you leave the civ with one city really work?

Makes sense to me, even if those people are under Mongol rule I'm sure they remember the peaceful times before the mongols came, put them to the sword and killed half the population in the process.

Alternatively the people of the city-states know the whole story too.

In the way I see it, I made peace for them and guaranteed no more war on the continent! For some reason the people in the past cities had a strange fear of horses though...