A second season has been commissioned. However the production schedule will be postponed due to the 2020 COVID-19 pandemic.
The plot loosely hints at the Korean myth of ancient city of Aseudal founded by the king Dangun, offspring of the heaven god and a female bear.
The drama writers got their inspiration from anthropological books like 'Sapiens: A Brief History of Humankind' and 'Guns, Germs, and Steel'.
The star-shaped bell, mandolin-shaped dagger and mirror (mentioned in the prophecies of the end of the world) are bronze age relics related to ancient Korean shamanism.
Song Joong-ki (Eun Som) and Kim Ji-won (Tan Ya) previously starred together in I discendenti del sole (2016) as Captain Yoo Si Jin and First Lt. Yoon Myeong Joo, respectively.