Emperor Mu of Jin

Emperor Mu of Jin, personal name Sima Dan (司馬聃), courtesy name Pengzi (彭子), was an emperor of the Eastern Jin Dynasty. While he "reigned" 17 years, most of these years were as a child, with the actual power in figures such as his mother Empress Chu Suanzi, his granduncle-in-law He Chong, his granduncle Sima Yu the Prince of Kuaiji, Yin Hao, and Huan Wen. It was during his reign that Jin's territory temporarily expanded to its greatest extent since the fall of northern China to Han-Zhao, as Huan destroyed Cheng-Han and added its territory to Jin's, and Later Zhao's collapse allowed Jin to regain most of the territory south of the Yellow River.