The old days were the floorboard of paper, ink, pen and inkstone. The inkstone, alias Mr. Mo, is the oldest treasure in Four Treasures of the Study. A study is a study. In the Northern Song Dynasty, Su Yijian wrote Four Books and Four Treasures of the Study, describing the types and authenticity of these four kinds of stationery. These stationery have a long history of production and a wide variety, with famous products and artists throughout the ages. For example, Xuan paper in Jingxian County, Anhui Province (formerly Ningguo House, which produced paper in the name of Xuancheng House), Hui ink in Shexian County (formerly Huizhou House), Hubi in Xing Wu, Zhejiang Province (formerly Huzhou House), Duanyan in Gaoyao, Guangdong Province, and Shexian County (formerly state house) with the same name as Duanyan.