When the circles of historical studies had disputes over the social and economic composition of the period of the Three Kingdoms in North Korea, Marx's posthumous work titled Pre-Capitalist Economic Formations was introduced into the country. At that time, the disputes were divided between the slavery society theory and the feudal society theory during the period of the Three Kingdoms. Pre-Capitalist Economic Formations was actively embraced by the researchers who argued the slavery society theory for the period of the Three Kingdoms. Representative members were Lim Geon-sang and Baek Nam-woon. They accepted Marx's “general slavery system” as an alternative to overcome the identity theory of Joseon history. Arguing the early feudal society theory for the period of the Three Kingdoms, Kim Seok-hyeong expressed his position that the specific and historical reality of Joseon history should come before theoretical issues. Their disputes came to an end after The Complete History of Joseon was published. The book explains Gojoseon and Buyeo as an ancient society of slave owners and the Three Kingdoms as a feudal society. In this process, the theoretical grounds of Pre-Capitalist Economic Formations were formally adopted in the ancient history of Joseon. The process and conclusion of the disputes over “Ancient Era” centered around the creative application of Marxism-Leninism to the history of Joseon and provided an important opportunity for the later historical studies of North Korea to get refracted and distorted from Marxist historical studies.