High Quality Content by WIKIPEDIA articles! The Prehistoric Korea is the era of human existence in the Korean Peninsula for which written records did not exist. It, however, constitutes the greatest segment of the Korean past and is the major object of study in the disciplines of archaeology, geology, and palaeontology.Geological prehistory is the most ancient part of Korea's past. The oldest rocks in Korea date to the Precambrian. The Yeoncheon System corresponds to the Precambrian and is distributed around Seoul extending out to Yeoncheon-gun in a northeasterly direction. It is divided into upper and lower parts and is composed of biotite-quartz-feldspar schist, marble, lime-silicate, quartzite, graphite schist, mica-quartz-feldspar schist, mica schist, quartzite, augen gneiss, and garnet-bearing granitic gneiss.