Because at the time of the war in Qin Chu, Chu Huaiwang volunteered to be a hostage in the State of Qin in order to avoid the suffering of Chu, and the Chu people admired him deeply. But Chu Huaiwang eventually died in a foreign land, and even the bones were not allowed to be transported back for burial. Therefore, the Chu people hate the Qin people very much. So if Qin really ruled the country, but as long as one person rebelled against Qin, many Chu people would join the rebellion.