It is the first time that remains of the Old Stone Age was discovered at the River Ryesong basin, one of the central parts of Korea lying between the Ahobiryong and Myolak mountains.

The cave was found in Sajong-ri, Singye County, North Hwanghae Province, where the teachers and researchers unearthed lots of remains dating back to the Old Stone Age, including five stone tools of three kinds, three bone tools and 732 fossil bones of 17 species of mammals, through comprehensive excavation.

Through an archeological study of a stone tool and palaeontological analysis of extinct species, they proved that the remains in the natural cave dates back to the latter term of the Old Stone Age.

The fossil bones of mammals, including weasel, water-deer, bear and lynx, in the site go to prove that the basin was a forest area with hilly, grassy and swampy lands and was subject to temperate climate like the present.

The stone tools and bone tools, estimated to be used for hunting animals and collecting plants, and fossil bones of mammals give a vivid description of the then human life.

It was clearly proved through the discovery of the remains in the natural cave that the Korean ancestors had lived in the vast area covering the Taedong River and the Ryesong River basins in the Old Stone Age, creating human culture.