AleksandraSucur

All the elder cast in The Litchi Road is from The Longest Day in Chang'an, as well as the director and the original creator. The setting is in the Tang Dynasty, taking place 10 years after the events in The Longest Day in Chang'an, so the vibe and the atmosphere is the same.
Last but not least, there are continuous references in dialogues (inspector He dreaming of being the emperor, while the same actors played the role of the emperor in The Longest Day in Chang'an) revoking the events in The Longest Day in Chang'an