Developer Sandy Petersen has given multiple explanations as to how the Koreans were added as a playable faction in the game's Conquerors expansion in 2000. On the Age of Kings Heaven forum in 2016, Petersen explained that the Koreans were chosen as one of a few candidate "Oriental" civilizations that could use the existing East Asian architecture art assets, along with the Khmers and Tibetans. He said that ultimately, attracting potential customers in South Korea was just one of several deciding factors.

Years later in 2025, he gave a different, contradictory account of events, stating that the Koreans were a last-minute addition handed down from Microsoft only five weeks before the project's completion. He also mentioned that one of the design decisions he made for Koreans was to give them free Archer armor upgrades. However, this bonus wasn't added to the game until Update 42848 in 2020, many years after Petersen's work on the game finished.