Potters in the district of Okawachi (Mt. Okawachi) produce Nabaeshima wares, which have a pore-free smooth body. Many consider them the best porcelain in Japan. In the olden days, they were made exclusively for the ruling family and not permitted for trade. Consequently, they were unknown to the West until the end of the nineteenth century. See Anneliese Crueger, Wulf Crueger, and Saeko Ito. "Modern Japanese Ceramics". Lark Books, New York (2007). p 60.