The series is based on the 2010 novel Princess Pyeonggang by a film director and screenwriter, Choi Sagyu.
The screenplay is inspired from "On Dal" folk tale, which is contained in historical record "Samguk Sagi" (The History of the Three Kingdoms of Korea). "Samguk Sagi" was compiled by Kim Bu-sik and published in 1145.
This series also reunites Kim So-hyun and Kim Hee-jung who previously worked together in Huayu: Hakgyo 2015 (2015).
On 24 March 2021, it was reported that there is a plan to re-film the first six episodes of the show in light of Na In-woo's replacement of Ji Soo and the expressed public interest by existing viewers to re-watch the first six episodes and new viewers to watch the previous episodes. The decision is also influenced by the positive reception to Na In-woo's acting and chemistry with female lead Kim So-hyun despite the circumstances of his casting.
On March 4, 2021, a KBS representative shared that filming scheduled for March 4 was canceled in light of Ji Soo's ongoing school violence controversy. On March 5, Ji Soo was removed as a cast member from the drama. Later that day, it was confirmed that Ji Soo was replaced by Na In-woo from episode 7 on-wards.