Yuejiaquan (岳家拳, literally Yue Family Fist) is attributed to Yue Fei, a noted General of the Song Dynasty, and uses mostly military-oriented attacks based on internal and external techniques. Its tricks stem from the relation of positive and negative and the five elements of the heart, liver, lung, spleen and kidney. Legend claims Yue taught the style to his soldiers who passed it down for generations after his death.
The style is mentioned towards the end of Yue Fei’s highly popular folklore biography The Story of Yue Fei published in 1684. In the novel, Yue Lei, Yue’s second son, uses it in a brawl against Zhong Liang, the instructor of a group of bandits who forcefully took over a local Taoist temple to Lord Guan. Their identities are revealed after Yue Lei uses a move recognized by Zhong Liang as The Black Tiger’s Theft of the Heart. Both realize their families have actually been friends for three generations.
(Wikipedia, https://en.wikipedia.org/wiki/Yuejiaquan)