Dwelling sites and earthenware similar to those found near Tumen River and Primorsky Krai were discovered in a 120,000 km² three-river plain located in northeast Heilongjiang, China. They are the pieces of evidence that the culture of ancient Korean tribal-state Okjeo, which originated near Tumen River, moved north to reach the plain. The people of Okjeo had lived on fertile land in the North for over 300 years and built large sites for castles. Over 250 sites of ancient castles were found in the area, the biggest of which is larger than the Earthen Fortification in Pungnap-dong.
A book titled “Okjeo and Yilou,” written by Professor Kang In-wook of the Department of History at Kyung Hee University, has new archeological findings of Okjeo and Yilou, northern Korean tribal states that existed from the fourth century B.C. to 246 A.D. and from the fourth century B.C. to 559 A.D., respectively. Professor Kang has studied the tribal states whose facts haven’t been well-known by traveling through Russia, China, and South Korea. “Studying the history of northern Korean tribal states is a way to stop China’s historical expansionism,” said Kang in an interview with The Dong-A Ilbo.
There are two main facts newly found from his research. There have been few scholars who believed the ruins of castles found in the three-river plain were built by the people of Okjeo. According to Professor Kang’s research, however, relics found in the plain are the same as those of Okjeo. Their move to the area can be explained given the lifestyle of the Okjeo people who traveled to areas suitable for grain farming. “Chinese scholars studying the three-river plain also admitted that these ruins belonged to Okjeo around the same time when my book was published,” said the professor.
Another academic finding by Professor Kang worth noting is that a steel ax estimated to have been made in the fourth century B.C. in the Yilou region across the basin of Songhua River was found the downstream of the Amur River. It is thought to be the oldest steel ax not only in China but also around the world.
Professor Kang who studies northern tribal states, a rare field for South Korean scholars, said he often receives a question whether the history of northern tribal states is that of Korea. “Dividing the history of northern tribal states into Korean’s and other’s is a shortcut to the distortion of Korean history,” the professor said. “Viewing the multilateral changes of history as they are is needed.”