Huang Xin is a fictional character in Water Margin, one of the Four Great Classical Novels in Chinese literature. Nicknamed "Guardian of the Three Mountains", he ranks 38th among the 108 Heroes and second among the 72 Earthly Fiends.
Background
Huang Xin is first introduced in the novel as a military officer from Qingzhou (; in present-day Shandong) serving under the governor, Murong Yanda. A skilled fighter trained by Qin Ming (who also serves as a military officer in Qingzhou), he fights well on both foot and horseback, wielding a sword called "Sword of Death" (). He earns himself the nickname "Guardian of the Three Mountains" after he once boasted that he can defeat the outlaw groups based on three mountains around Qingzhou: Mount Qingfeng (), Mount Twin Dragons (), and Mount Peach Blossom ().
Becoming an outlaw
Huang Xin is sent to Qingfeng Fort (; in present-day Qingzhou, Shandong), which is under Qingzhou's jurisdiction, to deal with Hua Rong, a renegade military officer who has defied his superior Liu Gao, the fort commandant, and provided shelter to the fugitive Song Jiang. He pretends to mediate the conflict between Hua Rong and Liu Gao, luring Hua into an ambush and capturing him, while Liu Gao's men arrest Song Jiang in the meantime. Song Jiang and Hua Rong are then secured in prison carts to be escorted to Qingzhou by Huang Xin and his men, with Liu Gao accompanying them.
En route to Qingzhou, the convoy is ambushed by the outlaws from Mount Qingfeng whom Song Jiang has befriended earlier. Outnumbered, Huang Xin is forced to retreat and hold up in the fort, while Liu Gao is killed by the outlaws. Huang Xin then reports the situation to Qingzhou's governor Murong Yanda, who sends reinforcements led by Huang Xin's master, Qin Ming, to deal with the outlaws.
However, Qin Ming ends up as the outlaws' captive and reluctantly joins them after they trick Murong Yanda into believing that he has betrayed and turned against the governor. Qin Ming then heads to Qingfeng Fort to meet Huang Xin, and manages to convince his apprentice to surrender and join the outlaws as well. Huang Xin then accompanies Qin Ming, Song Jiang and the others as they make their way to Liangshan Marsh to join the larger outlaw band there.
Campaigns
Huang Xin is appointed as a Tiger Cub Patrol Commander of the Liangshan cavalry after the 108 Heroes are fully assembled. He participates in the campaigns against the Liao invaders and rebel forces in Song territory after the outlaws receive amnesty from Emperor Huizong.
The final campaign against Fang La's rebel forces costs the lives of nearly two-thirds of the 108 Heroes; Huang Xin is one of the few lucky survivors. To honour Huang Xin for his contributions during the campaigns, the emperor awards him the title "Martial Gentleman of Grace" () and reinstates him as a military officer.