Strategy games such as chess and checkers are among the most ancient of games. But another game of strategy can also claim truly long history. The Chinese game Go dates back about 4000 years. Confucius referred to Go and his followers recorded this in his "Analects" written between 475 and 221 B.C. Popular in the East, Go eventually established more and more of a following in Western countries and the United States. Go is a game of territory, not movement. Players win by forming walls within their playing pieces, called "stones," which surround more territory than their opponent's stones do. Extremely challenging to play well in spite of simple rules, Go became popular in the United States during the 20th century. Today Go clubs in major cities sponsor official events.