[1] The series is based on the xianxia romance novel Zhu Yan by Cang Yue.

However, after being framed by the imperial consort Qiu Shui, he had to fake his death to escape from the palace.

Later, he meets Zhu Yan, a princess of Chi Yi clan, who becomes his disciple.

Principal photography commenced on March 2021 in the Hengdian World Studios.

[7] On March 29, 2021, the official Weibo of The Longest Promise announced the lineup and released the posters of the lead cast.