Shi Jingsi was from Yanmen (雁門; around modern Datong, Shanxi) and started his career as an assistant captain (牙校) there.
He was further promoted to an assistant general (裨將) in the major city of Taiyuan (in modern Shanxi), the capital of Li Keyong's administrative territory.
[3] In early 884, Li Keyong led his troops to attack the anti-government rebel force of Huang Chao, and Shi was the vanguard general to assist the besieged cities of Chenzhou (陳州; in modern Zhoukou, Henan) and Xuzhou (許州; in modern Xuchang, Henan).
With Li taking a long time to wake up, Shi, who also consumed much wine, climbed a tower and killed dozens of assassins using arrows.
[1] Li Keyong climbed the city wall to escape to safety, mourned Shi deeply, and began (although not immediately) a warfare with Zhu that would span several decades.