Strict Succession Rules of the Ming Dynasty

The Ming Dynasty strictly adhered to the principle of primogeniture (succession by the eldest son). The order of succession was as follows:

1.   The son born to the Empress.
2.   The eldest son from the emperor’s concubines.
3.   The emperor’s younger brother.

Succession Rules of the Qing Dynasty

The Qing Dynasty generally followed the principle of "establishing the rightful and eldest son" (favoring the Empress’s son or the emperor’s firstborn son). However, from the founding of the Qing Dynasty, emperors like Shunzhi and Kangxi adopted a family selection system to choose the heir.

Emperor Kangxi later changed the succession process to a primogeniture system, but after his chosen Crown Prince repeatedly made serious mistakes, he decided to depose him. This led to the introduction of a secret appointment system, where the emperor privately designated his successor without publicly announcing it. However, this method created potential risks if the emperor passed away without making a final decision.

From the reign of Emperor Yongzheng onwards, Qing emperors continued the tradition of keeping the successor a secret. Before his death, Emperor Yongzheng established the secret heir designation system called "Secret Edict of Succession" (秘密建储). This system was maintained by Emperor Qianlong and subsequent rulers.

Under this method, the emperor wrote a confidential decree designating his successor. Two copies of this decree were made:

•        One was kept by the emperor.
•        The other was sealed inside a box placed behind the plaque "Upright and Just" (光明正大), which hung above the throne in the Hall of Heavenly Purity (Qianqing Palace).

As a result, no one knew the identity of the next emperor until the reigning emperor passed away. After the emperor’s death, the regent ministers would unseal and compare the two copies of the decree in the presence of court officials to officially confirm the designated successor.

However, Emperor Xianfeng had only one surviving son and then Emperor Tongzhi, his son, passed away without any heirs. From then on, the secret heir designation system existed in name only and was no longer in actual practice