The Situation at the End of Han Dynasty: Dominating the Three Kingdoms

At the end of the Eastern Han Dynasty, all the heroes rose up and the world was in chaos. Although this was an era of heroic excitement, it was also an era of tragedy and suffering. A hundred years of wars left no one alive in the world, and also damaged all the heroes in the world. This gave the northern barbarians an opportunity to take advantage of and create the later Five Husties. A person from the future embarks on the road of time travel. What kind of changes can he bring to this era?