Records of the Three Kingdoms
Gongsun Zan, courtesy name Bogui, was from Lingzhi in Liaoxi. He and Liu Bei had both studied under Lu Zhi. Liu Bei depended on him early, and Zhao Yun began in his army.
With his white-horse volunteers he fought the Wuhuan and Yuan Shao and for a time held You Province. After defeats by Yuan Shao he fell back on Yijing, built high towers, and would not come out. In 199 Yuan Shao mined under the towers. Gongsun Zan burned himself. Much of his family died with him. The north was then the Yuan house’s until Guandu.
Romance of the Three Kingdoms
In the novel he enters early and leaves quickly, often only as Liu Bei’s background. The white-horse volunteers and the fire at Yijing are there, and short.
He is not a figure of the book’s second half. Yuan Shao’s victory over him is what makes Yuan Shao Cao Cao’s opponent at Guandu.
Reference: Wikipedia · Gongsun Zan