Historicity
Historically, there was no battle in Sishui Pass recorded in Chen Shou's Records of Three Kingdoms, the authoritative source for the history of the Three Kingdoms period. In fact, Sishui Pass and Hulao Pass are the same mountain pass near Xingyang, only different in name, despite them being separate in the novel. Another point is that Guan Yu was fighting remnants of the Yellow Turban rebels with Liu Bei in Xiapi during the campaign against Dong Zhuo, and could not have been in Sishui Pass to kill Hua Xiong.
However, the confrontation between Hua Xiong and Sun Jian did take place in history, but not in Sishui Pass. The story concerning Sun Jian and his scarf can be found in Records of Three Kingdoms, but the pursuer was Xu Rong instead of Hua Xiong. Contrary to the novel, Hu Zhen and Zu Mao were not killed in this encounter. After the defeat, Sun Jian reassembled his troops to score a victory against the combined forces of Hu Zhen, Hua Xiong, and Lü Bu in Yangren (陽人), where he had Hua Xiong executed.
Read more about this topic: Battle Of Sishui Pass