函谷关
In early 190, a coalition of warlords from the east of Hangu Pass started a military campaign aimed at freeing the central government and the figurehead Emperor Xian from Dong Zhuo control. Bao Xin brought along his younger brother Bao Tao () and his own troops to join the coalition and was appointed as acting General Who Destroys Barbarians (). The warlords nominated Yuan Shao, who had the highest prestige among them, to be their leader. Bao Xin, however, saw great potential in another warlord Cao Cao and befriended him. Later, Bao Xin and Cao Cao fought together at the Battle of Bian River () against Dong Zhuo's forces and scored a victory, but Bao Xin's brother Bao Tao was killed in action and Bao Xin himself was wounded.