Yi Zhi

"Yi Zhi" (弈旨, Yì zhǐ, Essence of Weiqi) by Ban Gu (班固 Bān Gù) is the oldest surviving text (1st century AD) devoted specifically to weiqi. It stated weiqi basics, differences between weiqi and liubo, weiqi variations, and how it conforms to Confucius.

Reference

• John Fairbairn's article on the Yi Zhi (formerly mindzine)