Cheng Yin

Cheng Yin is an officer who served Han Sui before joining Wei.

Historical Information
Cheng Yin was a general controlling parts of Guanzhong. He was born in Hedong prefecture (河東) of Sidi commandery (司隷). When Cao Cao invaded Guanzhong, Cheng Yin joined a coalition resisting Cao Cao with Ma Chao, Han Sui, and others. However, the coalition was defeated in the Battle of Tong Pass and he fled with Hou Xuan to seek refuge under Zhang Lu in Hanzhong. When Zhang Lu surrendered to Cao Cao, Cheng Yin followed.

Romance of the Three Kingdoms
In the novel, he is one of the Eight Riders of Han Sui. Together with Ma Chao's army, he forces the surrender of Chang An. He later fights against Cao Cao at Wei Nan, but he and his companion, Zhang Heng, were declared missing after the battle's conclusion.