The Longqing Emperor, also known by his temple name as the Emperor Muzong of Ming (明穆宗), personal name Zhu Zaiji, art name Shunzhai (舜齋), was the 12th emperor of the Ming dynasty; he reigned from 1567 to 1572. He was initially known as the Prince of Yu (裕王) from 1539 to 1567 before he became the emperor. He succeeded his father, the Jiajing Emperor. "Longqing", the era name of his reign, means "great celebration".

The Jiajing Emperor, also known by his temple name as the Emperor Shizong of Ming (明世宗), personal name Zhu Houcong (朱厚熜), was the 12th emperor of the Ming dynasty, reigning from 1521 to 1567. He succeeded his cousin, the Zhengde Emperor. "Jiajing", the era name of his reign, means "admirable tranquility".