Yunzi refer to special weiqi (Go) pieces manufactured in the Chinese province of Yunnan. At various times in history they have also been termed yunbian (云扁) and yunyaozi (云窑子). Though technically Yunzi refers only to sintered stones made of "yunzi" material, the term can also sometimes connote stones which are single-convex of any material. Yunzi-style stones made of jade for instance, were often presented to the reigning emperor and his court in ancient China.
Yunzi
Antique Yunzi produced in Ming dynasty
Go is an abstract strategy board game for two players in which the aim is to capture more territory than the opponent by fencing off empty space. The game was invented in China more than 2,500 years ago and is believed to be the oldest board game continuously played to the present day. A 2016 survey by the International Go Federation's 75 member nations found that there are over 46 million people worldwide who know how to play Go, and over 20 million current players, the majority of whom live in East Asia.
Go is played on a grid (usually 19×19). Game pieces (stones) are played on the grid line intersections.
Model of a 19×19 Go board, from a tomb of the Sui dynasty (581–618 CE)
Painting of a woman playing Go, from the Astana Graves. Tang dynasty, c. 744 CE.
Li Jing playing Go with his brothers. Detail from a painting by Zhou Wenju (fl. 942–961 CE), Southern Tang dynasty.