Star, Kim Eun-hee discussed the significance of exploring the concept of Han in the special episode. Whilst the creator began to delve into the idea through the creation of Ashin's character when writing the second season, Kim Eun-hee wanted to further examine the collective trauma, grief and resentment born from the experiences of tragedy in the special episode. The writer expressed her desire in depicting Han in the story, stating that "I always wanted to write a story about the feeling of Han. And in the previous seasons, it’s usually focused on the dominating power such as Prince Chang and the established people who lead the story. And then I came to think of the northern part of Joseon and the ones who are actually dominated by these people. So regardless of whether it is Joseon or another country, I think the people who are dominated have that same feeling (of Han)." Filming Principal photography for the first two seasons took place on location in Seoul, South Korea, including the Gyeonggi Province and North Gyeongsang Province between 2018 and 2019. Filming for Kingdom: Ashin of the North took place in Jeju Island in 2020. Casting Actor Song Joong-ki was courted for the lead role but declined. In September 2017, it was reported that Ju Ji-hoon, Ryu Seung-ryong, and Bae Doo-na were in talks to star in the series. In November 2019, it was reported that Jun Ji-hyun would star in the second season. After the announcement for the special episode, it was confirmed that Jun Ji-hyun and Park Byung-eun would reprise their respective roles in Kingdom: Ashin of the North. Additionally, it was confirmed that Kim Shi-ah, Koo Kyo-hwan and Kim Roi-ha were cast in the special episode. Prior to the premiere of the second season, Joo Ji-hoon stated in a Forbes interview, that he signed on to star in the series, due to his faith in the project. He adds that "From the refreshing subject matter to writer Kim Eun-hee’s exciting script, direction by director Kim Sung-hoon—and the cast members from season one—all these factors convinced me to continue on the journey to season two". Furthermore, he was excited at the prospect of a new director, joining the series in the second season, commenting that "Park In-je joined us for season two, and the new system of ‘making a TV series with people who make films’ was fascinating. The