The Ru kiln located in Linru County of Central China's Henan Province represented another major celadon school that rose in northern China in the Song Dynasty (960-1279). Ru Kiln refers to a official kiln in Linru County catering to the Northern Song rulers; the kiln's products were known as Ru ware porcelain. The Northern Song rulers, considering the white porcelain vessels of Dingzhou unsuitable for use because of their rough mouth-rims, sent personnel to establish kilns in Ruzhou to manufacture celadon. In the eyes of the people of the Song Dynasty, the celadon of Ru ware ranked first in quality among all northern celadon ware.
