Yanggubaekto (kaolin) refers to a weathered soil of garnet granite gneiss, the Precambrian base rock distributed over the areas of Yanggu-gun and Hwacheon-gun. The main body of the rock is Mt. Haesan (1,194m above sea level). The white clay of Bangsan-myeon in Yanggu-gun has been excavated in many other sites: Seonwoogol in Jangpyeong-ri, Seonan in Hyeon-ri, the riversides of the Suyipcheon in Geumak-ri, Omi-ri and the peak of Seonggokryeong. These sites form a large vein of white clay across the Bangsan area. The Yanggubaekto has a low content of iron oxides at 0.5% which dramatically enhances the color development of white porcelains; being as white as rice powder, it has been the finest material for the production of Joseon white porcelains. The Bangsan area in Yanggu-gun was a principal producer of the white clay for royal porcelains during the Joseon Period. In particular, the praying porcelain of the founder of the Joseon Dynasty, Yi Seong-gye, which was excavated in Wolchulbong of Mt. Geumgang revealed a prayer, followers and a master craftsman as well as inscriptions verifying the producing location; an epitome of the new dynasty’s perspectives has been contained in the white porcelain of the Bangsan in Yanggu. Starting around the 14th century at the end of Koryo Dynasty, the area’s production of the porcelain thrived thanks to abundant water supply from Suyipcheon (stream), firewood and high-quality white clay, Since Saongwon (royal kitchen) and a government kiln were established in Gwangju in Gyeonggi Province in the late 15th century, the Bangsan has served as a principal producer of white clay for white porcelains exclusively for the royal palace.