Kim, Yonyong is the one who introduced the concept of Proto-history in Korean archeology for the first time. Kim, Yonyong(金元龍) set up the Proto-three Kingdoms Period(Proto-history) in the meaning as the transitional period between prehistoric period and historical period, and the Three Kingdoms Period of Proto-history stage. In the end of the 19th century, Japan already used the concept of Proto-history in the anthropology area, which was influenced by archeological stratigraphy of Europe. The appearance of the concept of Proto-history in Korea was triggered by Hoehyeon-ri shell mound in Gimhae which was researched in the Japanese colonial era. Based on the relics excavated in Hoehyeon-ri shell mound in Gimhae(金海 會峴里 貝塚), the concepts like Gimhae period and Gimhae-type pottery were set up. In 1972, Kim, Yonyong initially suggested the concept of Proto-three Kingdoms Period substituting for the existing Gimhae period. However, the introduction of the name as Proto-three Kingdoms Period caused numerous controversies of periodization. Representatively, as an objection to the name as Proto-three Kingdoms Period, the argument of iron age(鐵器時代論), the argument of three Hans period(三韓時代論), and the argument of Gojoseon period(古朝鮮時代論) appeared. And regarding the upper limit of Proto-three Kingdoms Period, various reference points were presented such as around AD, installation of Nangnang(樂浪) commandery, and appearance of Triangulated clay-stripe pottery. Also since the issue of genealogy and period of Tanalmun pottery(打捺文土器) in proto-three Kingdoms Period was brought up, the controversy of gray pottery has been accelerated even till today. This controversy was expanded to the issue of overall material data of Proto-three Kingdoms Period such as Jungdo-type plain pottery. Like this, since the introduction of the concept of Proto-three Kingdoms Period(Proto-history), various commonly-accepted theories surrounding periodization and nature of material data have been repetitively set up and discarded. However, despite each argument, it does not reach the satisfactory definition that could meet all the conditions of the concept of Proto-history. However, there is no doubt that the controversy process led by the scholars in the past has become the basis of current Korean archeology, so even the scholarly limitation is good enough to get academic evaluation.