Sima Yong

Sima Yong (司馬顒) (before 274 - c.late January 307), courtesy name Wenzai (文載), was a Jin dynasty imperial prince and briefly a regent for Emperor Hui. He was the seventh of eight princes commonly associated with the War of the Eight Princes. His title was the Prince of Hejian (河間王), but he did not receive any posthumous names.

Though a distant cousin of Emperor Hui, Sima Yong was garrisoned at the important city of Chang'an to guard the Guanzhong region. When the Prince of Zhao, Sima Lun usurped the throne in 301, Sima Yong initially sided with him, but later joined the Prince of Qi, Sima Jiong, and the Prince of Chengdu, Sima Ying, in their coalition to restore Emperor Hui.

After the restoration, Sima Yong grew disaffected with the regency of Sima Jiong and rekindled his alliance with Sima Ying, who vied to become Emperor Hui's crown prince. They campaigned against Sima Jiong and later the Prince of Changsha, Sima Ai at Luoyang, eventually gaining control of Emperor Hui in 304. When Sima Ying was defeated by the Prince of Donghai, Sima Yue and his allies later that year, Sima Yong forcibly seized Emperor Hui for himself and relocated him to Chang'an. Under his paramountcy, he attempted to negotiate peace with Sima Yue and had the empire governed under two courts; the Western Court in Chang'an and the Eastern Court in Luoyang. In fall 305, Sima Yue, with a large force in the east, formed a coalition against Sima Yong to bring Emperor Hui back to Luoyang. Sima Yong was defeated the following year and lost the emperor, but he was able to recapture Chang'an and held out in the city before he was assassinated in early 307.