During the Tianbao period of the Tang Dynasty, Li Shande, a petty official in Chang'an, was suddenly given a task to bring fresh lychees from Lingnan. The lychee is perishable, and becomes tasteless three days after it leaves the branch, and Lingnan is more than 5,000 miles away from Chang'an, so this is an impossible task. But for the sake of his wife and daughter at home, Li Shande was determined to give it a try.