In a mythical land called Arth, the inhabitants of the ancient city of Arthdal contend with power struggles, while some encounter love along the way. Eunseom goes through hardships to bring his tribe back to life and learns of his true origins in the process. It depicts the story of what happens in Arth approximately a decade later. Over the course of more than eight years, Arthdal succeeded in suppressing the massive rebellion of the tribes slaughtered by Ta Gon in Season 1, and the Agos finally achieved the reunification of 30 clans after 200 years under the leadership of Eun Seom. In Season 2, Ta Gon’s Kingdom of Arthdal and Eun Seom’s Ago Union are set to face an inevitable great war. Eun Seom is the ruler of the East now. Tan Ya is the successor to the Wahan clan. The story set eight years after Ta Gon has become king.