Chengjia, literally the "House of Cheng", was named after its capital Chengdu. It was also called the Cheng dynasty or Great Cheng, meaning "complete" or "accomplished".
Founding
After Wang Mang usurped the throne of the Western Han dynasty and proclaimed himself emperor of the Xin dynasty in 9 AD, he promoted Gongsun Shu to be the governor of Daojiang. In 23, rebels overthrew Wang Mang and restored the Han dynasty under Liu Xuan, the Gengshi Emperor. Gongsun Shu ostensibly declared his allegiance to Gengshi while defeating an army sent by Liu to take over Shu. He assumed the titles General Fuhan and Governor of Shu Commandery and of Yi Province. The following year, he declared himself the King of Shu under the Han empire, with Chengdu as his capital. In the fourth month of 25 AD, Gongsun Shu declared himself emperor in defiance of Gengshi, whose throne was being threatened by the forces of Liu Xiu. He named his self-declared empire as Chengjia and adopted the era name Longxing. A few months later, Liu Xiu proclaimed himself Emperor Guangwu of the restored Han dynasty.
Expansion and consolidation
Chengjia initially only had direct control of the Sichuan basin. Soon Ren Gui took control of Yuesui Commandery and submitted to Chengjia. Gongsun Shu sent general Hou Dan to take over Hanzhong in the north and Ren Man to Jiangzhou to the east, and took control of the entire Yi Province of the Han dynasty. Other rebel forces who were defeated by Emperor Guangwu, most importantly Yan Cen and Tian Rong, also submitted to Chengjia. The warlord Wei Ao, who controlled eastern Gansu and was under constant pressure from the Eastern Han, submitted to Chengjia. Gongsun Shu bestowed on Wei Ao the title King of Shuoning, and sent a force to support him. At the time, Emperor Guangwu was embroiled in the civil war engulfing much of China, and Gongsun Shu's advisor proposed attacking Han while it was still weak. However, despite Chengjia's vast territory, its population comprised only 7% of China's total at the time, and Gongsun Shu rejected the proposal. Still, Chengjia remained Han's most dangerous rival, and Guangwu took care not to antagonize Gongsun Shu, even addressing him as "emperor" in his letters.
Demise
Chengjia remained independent for more than ten years, owing to the natural defenses enjoyed by the Sichuan basin, and the unsettled conditions in the newly established Eastern Han. In 34, Emperor Guangwu conquered Gansu, held by Wei Chun, the son and successor of Wei Ao. Chengjia sent general Li Yu with a force of more than 10,000 to assist Wei Chun, to no avail. After Guangwu conquered the rest of China, he dispatched a force led by Cen Peng to conquer Chengjia. Below the Three Gorges on the Yangtze, Chengjia's eastern frontier, Chengjia forces built a floating bridge across the river mounted with war towers, linking fortifications on both banks. In April or May of 35, aided by favourable easterly wind, Han naval forces sailed upstream to the bridge and attacked it with torches. The wooden bridge caught fire and burned down, removing the obstacle to Han invasions by water. Despite the initial success, the Han campaign was slow and difficult because of natural obstacles. Moreover, Chengjia sent assassins who managed to kill general Lai Xi and then Cen Peng, chief commander of the Han forces, which were subsequently led by Wu Han and Zang Gong. The Han forces reached Chengdu in December of 36, with only a week's supplies left. They were on the verge of accepting failure and withdrawing, when Gongsun Shu decided to personally lead an attack on the Han forces on 24 December. Wounded in the battle, he died in the night, and the defenders of Chengdu under Marshal Yan Cen surrendered the following day, marking the end of Chengjia. Two days later, Wu Han granted his soldiers permission to loot Chengdu and burn down the imperial palace. He massacred Gongsun's extended family including his wife and children, as well as Yan Cen and his family. Many other people were also killed. The court musicians of Chengjia were later sent to the Han capital Luoyang.
Government
Gongsun Shu modelled his government after that of the Han dynasty, and appointed his advisor Li Xiong and his younger brothers, Guang and Hui, as the Three Excellencies. Gongsun Guang was the Grand Marshal, Gongsun Hui the Minister of Works, and Li Xiong the Minister of the Masses. After Yan Cen and Tian Rong submitted to Chengjia, Yan was appointed Grand Marshal and enfeoffed as King of Runing, and Tian was enfeoffed as King of Yijiang.
Coinage
Gongsun Shu abolished Han dynasty copper coins and issued his own Wu Zhu coins for Chengjia, which resemble the Han Wu Zhu coins but are made of iron, possibly because Sichuan was then China's dominant producer of the metal. However, the change of currency proved unpopular with the people.
