We must clarify a concept: all the regimes in history with the name of "Han" will not add other words to the front, that is to say, they will all call themselves "Han"; the preceding words are added by later generations. The reason why Liu Bang named the dynasty he established "Han" is because when Xiang Yu first divided the Eighteen Road Princes, he was given the title of "King of Han", and he also used this banner to order all the people and horses, and naturally maintain continuity after unifying the world.
When Liu Bei was proclaimed emperor, he used the name "inheriting the great unification in Xichuan", which of course was followed by the unification of the Han Dynasty, and regarded himself as orthodox. This is also the reason why Liu Bei and Zhuge Liang have always called the northern expedition to attack Cao Wei, according to the "Spring and Autumn" calligraphy, the crusade is to fight against the thieves of the chaotic courtiers, that is, on the side of the Shu Han, Cao Wei has always been regarded as the chaotic thief of the Han Dynasty, and indeed it has always been called Cao Wei.
Chen Shou, the author of the Romance of the Three Kingdoms, was originally an official of Liu Bei's regime, and later entered the Jin Dynasty, where he was responsible for writing the history of the country. Although he wrote the history of the three countries in the "Book of Wei, Shu, and Wu" to show the objective facts of the three kingdoms; however, as far as the whole book is concerned, he had to take Cao Wei as the orthodox, and only the "Book of Wei" had "Ji" to call the emperor "emperor", while the Book of Shu and the Book of Wu only "chuan" the emperor and only called "lord". This is because of the early establishment of the Jin Dynasty, most of the dynasties are Wei relics; the second is because the Jin Dynasty was subject to Wei Zen, and whether Cao Wei was orthodox or not directly affected the success of the Jin Dynasty. If liu Bei's regime in Western Shu is recognized as "Han", it would deny the legitimacy of the Cao Wei Zen Dynasty. If Cao Wei was a usurper, the legitimacy of the Jin Dynasty would also become a problem, which is called "pseudo-Wei is pseudo-Jin".
The title of "Shu Han" or "Shu" is all in order to distinguish the Eastern Han, Western Han, and Shu Han, and in terms of blood, they are in the same vein, but the middle is cut off. Liu Bei served as emperor for 2 years and died of illness in Yong'an Palace in 223 AD. Liu Chan, who reigned for 42 years, was smuggled into Yinping by Deng Ai, and the soldiers came to Chengdu, Liu Chan went out of the city and surrendered, and shu Han perished.
Interestingly, it is said that the weak and incompetent Liu Chan is "an unsupportable Adou", but among the emperors of the Three Kingdoms, Liu Chan, who reigned for 42 years, was the one who reigned for the longest time (counting the history of Chinese emperors, reigning for 42 years is also a very long record, many of which are generally in the twenties and 30s, even the emperor of the first emperor of the ancients, Tang Taizong Li Shimin, also reigned for 23 years). This may be a joke that history has made for everyone.