1, the chronicle of the Ming dynasty mentioned that the chess pieces came from Yunnan, with Yongchang as the top. It shows that the quality of Yunnan Go is outstanding, especially Yongchang. Why Yunzi, one side of water and soil gives birth to one side of products?
2. In the Annals of Yongchang written by Guangxu in Qing Dynasty, the materials and techniques made by Yongji were briefly described: Yongji is the best chess in the world, and its making method is to grind agate stone and amethyst into powder, add lead nitrate, and then add medicinal materials to forge it.