A second season has been commissioned. However the production schedule will be postponed due to the 2020 COVID-19 pandemic.
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.
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.
Song Joong-ki (Eun Som) and Kim Ji-won (Tan Ya) previously starred together in Descendants of the Sun (2016) as Captain Yoo Si Jin and First Lt. Yoon Myeong Joo, respectively.