By the way, if you guys are wondering what's going on in the trailer, it's basically the very opening of the Romance of the Three Kingdoms period proper (after that Yellow Turban nonsense).
It's the Battle of Hulao Gate.
The fatass is Dong Zhuo, the inspector (basically governor) of Liang province in China. The dude with the red feather next to him is Lu Bu obviously. They hail from an area of China that specializes in mounted combat. Very similar to the Hunnic and Mongolian peoples. Prior to the event, Dong Zhuo was invited into the capital city by a dumbass who doesn't deserve to be named to restore order after a bunch of sexless dumbasses were being dumbasses. They were eunuchs in case you were wondering why I said that.
Anyway, since he was basically given a free pass by the abovementioned dumbasses to bring a full army right into the heart of the empire, he decided to just stay there and rule. Sounds fair to me honestly. I mean if your relatives made you drive from Seattle to Florida just to settle a dispute with a large army, you kinda deserve some shit.
Dong Zhuo ruled like a dumbass, raping and pillaging everything. This caused all the lords to rebel and they gathered together under the banner of another dumbass by the name of Yuan Shao (to be fair to him, Yuan Shao only became a dumbass after tasting power, he was pretty cool before). Anyway, some shit happens, and by some shit I mean no shit happens. Cause all the lords spent all their time being dumbasses and not doing anything.
Dong Zhuo brings basically his entire army to Hulao Pass and they taunt the alliance of dumbassery to come out and fight them. Lu Bu does most of the taunting. Some dumbasses go out to fight him, and by some I mean a lot, and they get their asses kicked. By asses I mean they were killed. So the dumbass lords become too scared to do anything. Incidentally, during this battle Cao Cao and Liu Bei were there too. But neither were lords of anything really and Cao Cao only had a small contingent of men. Liu Bei only had his two friends Guan Yu and Zhang Fei. In the trailer, Cao Cao is the guy who moves those pawns on the map and Liu Bei is the guy making the oath in the peach tree grove.
Anyway, after a bit of getting their asses kicked. Legend goes that Guan Yu and Zhang Fei, two nobodies at the time, went out and fought Lu Bu. Zhang Fei fought solo at first. It was here that Zhang Fei basically called him a triple bastard. Because Lu Bu abandoned his real father, betrayed his foster father (for a horse...), and was now the lapdog of his third father. Lol.
Anyway, Zhang Fei started losing, and in true fashion to their real historical characters, Guan Yu interrupted this manly 1 on 1 duel and now fought Lu Bu 2 on 1. How chivalrous. But of course I expect nothing more from a bunch of rapist country-bumpkin bandits. But enough about that. See Liu Bei felt left out and went and fought him too, so now this duel was 3 on 1. How fair. Lu Bu lost and retreated. Which basically ended the battle. This also teaches us that no one gives a shit about honorable duels as long as you win.
Now the fun part. You'd think after winning this defining battle, the dumbasses would had won the entire war. I mean, for all intents and purposes they could. It would have been easy to run down with the alliance troops and obliterate the remainder of Dong Zhuo's fatass army. However, reality begged to differ.
The alliance was not a true alliance. These dumbass lords were more interested in their own profits than the Empire as a whole. They had absolutely no intention of sacrificing or risking their troops to defeat a relatively sizeable army. So they sat and squabbled with each other with only basically two lords actually doing anything (and failing). One of those was Cao Cao, who barely even had an army and got obliterated. The legend goes that it was at this point that Cao Cao realized he was surrounded by morons and if the Empire had any hope of being reunited, he had to do it himself. The other was Sun Jian, the father of those who would eventually form the Wu "kingdom". Sun Jian was a pretty cool dude. So Dong Zhuo managed to make it back to the capital, which he promptly moved to a completely different part of the country. It would be many, many years later before he would be killed and defeated.
Thus began the period of strife. Now the empire was basically split into a couple dozen random-ass dumbasses of varying degrees of legitimacy as everyone scrambled to claim whatever they could for themselves.
A few years after that the map would basically look like this:
p.s: This entire battle was fictional btw. Didn't happen in real life.