After the An Lushan Rebellion, the Hexi Corridor of the Great Tang fell, leaving the Western Regions isolated. Guo Xin led the Anxi Army to hold out in Kuqa for over thirty years, with all the soldiers in the city turning white-haired. Liu Huan, a young traveling merchant, stepped into the Gobi Desert with a caravan, and after being harassed by Tubo raids, accidentally entered the isolated city. At first, he only wanted to make money and return home, but he was deeply shocked by the sincere dedication of the defending soldiers and civilians protecting their land with their lives. From a bystander merchant to resolutely abandoning profit to join the war, he experienced blood-soaked defense of the city firsthand, witnessing Guo Xin and the veterans' unwavering national integrity of not yielding an inch of land. When Guo Xin heroically died for his country, Liu Huan took over the banner of the Anxi Army, continuing the belief of "Once a soldier, defending the land for a lifetime," and guarding the territory of the Tang Western Regions with his flesh and blood.