Emperor Muzong Zhu Zaihou (1537 - 1572), the third son of Emperor Shizong Zhu Houcong, ruled the Ming Dynasty for six years with the reign title "Longqing".

Zhu Zaihou was born in 1537. As his mother Concubine Dukang was no longer favored by the emperor and he was not the eldest son, Zhu Zaihou seldom got his father's love. In 1553, when Zhu Zaihou was just 16 years old, he began to live independently at Yuwang Mansion. The 13-year life at the mansion gave Zhu Zaihou much access to various aspects of social life and enabled him to know about the conflicts and crises of the Ming Dynasty. The decadence of the imperial laws, the corruption of the bureaucrats, the misery of the commoners, and the domestic trouble and foreign invasion caused him to care about the court affairs, which exerted a great influence on his dealing with state affairs after ascending the throne.

During his reign, Zhu Zaihou would let go of his officials to bring their talents into full play. The society was stabilized at that time and the economy greatly improved compared with that of previous regime. It played an important transitional role on the development process of the last prosperous period of the Ming Dynasty.

In 1572, Zhu Zaihou died of illness at the age of 36. He was buried in the Zhaoling Mausoleum.