Emperor Jiajing, 12th ruler of the Ming Dynasty (r. 1521-1567). Personal Name: Zhu Houcong, Zh? H?uc?ng. Posthumous Name: Sudi, S?d?. Temple Name: Shizong, Sh?z?ng. Reign Name: Ming Jiajing, Ming Ji?j?ng. The Jiajing Emperor was the 12th Ming Dynasty Emperor of China who ruled from 1521 to 1567. His era name means 'Admirable Tranquility'. After 45 years on the throne (the second longest reign in the Ming Dynasty), Emperor Jiajing died in 1567  possibly due to mercury overdose  and was succeeded by his son, the Longqing Emperor. Though his long rule gave the dynasty an era of stability, Jiajing's neglect of his official duties resulted in the decline of the dynasty at the end of the 16th century.