How many years has Yan Song been the chief assistant?

Yan Song had been the chief assistant for twenty years.

Zhang Juzheng had been the chief assistant for ten years.

Xu Jie had been the chief assistant for seven years.

Zhang Juzheng served as the chief assistant of the cabinet for 10 years.

Yan Song had been the chief assistant for twenty years.

Yan Shifan had once held the position of chief assistant during the Jiajing Emperor of the Ming Dynasty. Yan Shifan was the son of Yan Song, the chief assistant of the Jiajing Dynasty of the Ming Dynasty. He became an official after entering the Imperial College by borrowing his father's power. He had served as a junior official of the Shangbao Department and the left assistant minister of the Ministry of Works. When Yan Song became the chief assistant again, he handled government affairs on behalf of his father and was known as the number one genius of the Jiajing Dynasty. Therefore, it could be concluded that Yan Shifan had held the position of chief assistant in the Jiajing Dynasty.

Yan Song served as the chief assistant during the Jiajing period of the Ming Dynasty, but the given search results did not mention the specific time he served as the chief assistant. Therefore, I don't know exactly when Yan Song became the chief.

Yan Song was in power for 20 years.

Xia Yan was Yan Song's previous chief assistant.

Xu Jie was the head of the cabinet after Yan Song.