Huang Shigong (Chinese: 黃石公; lit. 'Yellow Rock Old Man') is a semi-mythological figure and Taoist hermit who lived between the Qin Dynasty and Han Dynasty. He gave Zhang Liang a treatise on military strategy called Huang Shigong San Lue (The Three Strategies of Huang Shigong) and the Lingqijing divination manual that allowed Zhang Liang to transform into an adept statesman and powerful war theorist. Source: Wikipedia (en)