Liu Biao
In 198, when Liu Bei was planning to break free of Cao Cao's control by leaving the imperial capital Xu (許; present-day Xuchang, Henan), he sent Sun Qian and Mi Zhu to secretly contact Cao's rivals Yuan Shao and Liu Biao and form alliances with them. After Yuan Shao's death in 202, Liu Biao once wrote to Yuan Shao's third son and successor, Yuan Shang, and mentioned the rivalry between Yuan Shang and his eldest brother Yuan Tan. Liu Biao wrote: "Whenever I discussed this issue (the rivalry between you and your brother) with General Liu (Liu Bei) and Sun Gongyou, I feel very upset and heartbroken." Both Liu Bei and Liu Biao highly regarded Sun Qian.