The State of Ruyin in the Western Jin Dynasty was located in the territory of Yu Prefecture in the Western Jin Dynasty, and was a feudal state with counties as its state. Ruyin County administers eight counties, namely Ruyin, Shen, Yuanlu, Gushi, Gongyang, Xincai, Song, and Baoxin.

The first King of Ruyin, Sima Jun. When introducing the Fufeng King, we said Sima Jun, who was the seventh son of Sima Yi and his mother was Lady Fu. Sima Jun was very intelligent since he was a child, and his morality was also good, and he was an excellent rising star in the Sima family. After the establishment of the Western Jin Dynasty, Sima Jun was given the title of King of Ruyin and the Governor of Yuzhou. In the sixth year of the Tai Dynasty (270 AD), Sima Jun moved to the post of General of Zhenxi ( Zhenxi General , Envoy Jie jie , and Governor Yongliang ( 雍梁 ) , and succeeded his deposed brother Sima Liang the Prince of Runan , who was appointed to guard Guanzhong , and added the costume of Gong Mian as a servant. After that, he was busy calming down the chaos of bald tree function. In August of the third year of Xianning (277 AD), Sima Jun was renamed the Prince of Fufeng.
The King of Ruyin, Sima Mo. The King of Ruyin after Sima Jun was Sima Yan's fourteenth son, Sima Mo. Sima Mo was given the title of King of Ruyin during the reign of Sima Yan Taikang. However, he died in the seventh year of Taikang (286 AD) at the age of eleven.
The last King of Ruyin, Sima Qian. The third son of Sima Lun, he was created the Prince of Ruyin in April of the first year of Yongkang (300 CE), the Following Year he was renamed the Prince of Guangping, and was eventually killed along with his father Sima Lun.