In 202, Sun Quan killed Sheng Xian, the Administrator () of Wu Commandery. Some of Sheng Xian's associates and protégés went into hiding in the mountainous areas of Jiangdong. In the following year, Wu Jing, the maternal uncle of Sun Quan and his brothers, died in office while serving as the Administrator of Danyang Commandery (). Sun Yi, who was 19 years old then and held the rank of a Lieutenant-General (), was appointed as the new Administrator of Danyang. Danyang was adjacent to Wu Commandery, so Sun Yi reached out to some of the disgruntled followers of Sheng Xian, enticing them to Danyang and offering them positions in the Danyang administration in order to stabilise the region. Two of these men, Gai Lan () and Dai Yuan () came to work for Sun Yi. Dai Yuan was appointed as a Civil Assistant () while Gai Lan was given a high military command with the slightly irregular title "Grand Chief Controller" ().