Su Qin
According to this written evidence, Su Qin’s era followed that of Zhang Yi, during the reign of King Zhao of Yan. In conjunction with Gong Sun Yan, Su Qin continued Zhang Yi's mutual confrontation with the Horizontal Alliance of Xi Shou. Su Qin had four older brothers: Su Dai, Su Li, Su Bi and Su Hu. Under his teacher Yu Qi, Su Qin studied all aspects of the operations of the Vertical Alliance and the Horizontal Alliance. He also pored over the books in Yu Qi’s collection and found one titled "Minister Yin Fu’s Plan", which Su Qin studied hard for many years, and accepted that its methods would be enough to gain the support of the reigning monarch.