The chang guan(long headgear)recorded in the Carriage and Clothing Treaties of the Book of the Later Han is a unique style under a capping ceremony called Guanzhi.It is also known as the"Liu family guan,""magpie tail guan,"etc.,that belongs to the Chu state capping system.Archaeological discoveries have confirmed that in the early Qin and Han dynasties,various capping systems of similar shapes were also popular in the centralized area in addition to the Chu style.It can be collectively referred to as the chang guan capping system to understand the differentiation.Unlike the popularity of the jinxian guan and the wubian daguan,the chang guan shows a clear step-by-step development in Chinese costume history due to its connection with the emperor Gaozu of the Han dynasty.Through the two reforms of the Chinese costumes,namely one in 199 BCE and one in 59 BC,chang guan received two upgrades of the symbol of identity.It was upgraded from a common official headgear to a court headgear,and then to a sacrificial headgear.The progressive development pattern of chang guan in the Han dynasty from the ordinary level to the ritual level is a common and provoking historical phenomenon in the course of ancient Chinese costume history.It reflects the general rules in the Han dynasty,even in the entire ancient Chinese costume history,such that each dynasty consciously imitated and borrowed certain elements from the ancient costumes when setting its regulations on sacrificial attire.As the chang guan of the Han dynasty,its unusual development was the result of the political needs.The ritual process of the chang guan was a profound interpretation of the ancient Chinese costumes,especially the sacrificial clothing,as a tool of political rule.