In China's fairy tales, what does the king of longevity mean?

In China mythology, the king of longevity refers to Peng Zu.

Peng Zu, one of the pioneers of Taoism in the pre-Qin period. His last name is Ken. One is Peng Keng, the third son of Lu Zhong. The founder of Peng Zu is also known as "Zhuangzi" metaphysics: "Yao Feng is in, and his way can be ancestral, so he is called Peng Zu." "Chu Ci Tian Wen": "Peng Keng splashed pheasants, what is the emperor? How long can my husband last? " Wang Yi's note: "Peng Keng, Peng Zu also. Hong Xingzu added a note in The Legend of Immortals: "Peng Zu's surname is Yan Mingkeng." ... Yao was sealed in Pengcheng. Liu Xiang's Biography of Immortals is an old book title written in Han Dynasty, which listed Peng Zu in the immortal world and called him "Immortal Master". Peng Zu is a native of Peng Guo (now Tongshan, Xuzhou, Jiangsu). A Brief History of Clans records: "Peng Zu was founded in Peng, and later people took the country as their surname. Peng is also a surname. "In the early Song Dynasty, the article Le Shi Peng Cheng County Records quoted the story of Pengmen as saying: Peng Zu, a sage of Yin, was the great-grandson of Zhuan Xu, who was 767 years old at the end of Yin Dynasty. In other words, Peng Zu should be about 3,500 years old by now.