Taken from: "Zhengzhong Nanpai Shaolin: Paihemen Shihequan" ("The Orthodox/Original Southern Shaolin Style: White Crane Gates - Feeding Crane Fist"). All information here comes from "Shaolin Bronze Man Book".
THE ORIGINS OF WHITE CRANE
At the beginning of Chin dynasty in Jiolien Mountains (Fukien province of China), the temple of Shaolin became a place of conflict between the oppressed nation (supported by Shaolin Buddhist Monastery in Southern China) and the government of foreign origins, the Mongols. The government therefore ordered to burn the temple. Monks who escaped death had to run away.
After the destruction of Shaolin one monk named Fong, Huei-shi escaped, and hided in Fuzhou branch of Shaolin. He possessed the knowledge of Shaolin Shipa Lohan Quan (18 Monk Fists) style. Fong, Huei-shi had a daughter named Chi Nian, who lived in Bizuei Lien-An in Shaolin Temple. Since childhood she learned Wushu from her father. Chi Nian was very fast learner, improving so quickly, that she understood the sentence of Shaolin Wushu in only four years.
It is said that Fong, Hue-Shi was murdered by neighboring village's members, who were jealous for his Quanfa skills. From that moment on, Fong, Chi-Nian promised herself to revenge her father.
On one day, while on a way back from the river where she was washing clothes, she saw a white crane sitting on the roof. Worried that bird may dirty her washing, she tried to scare it away with a stick. White attempting to hit the crane's head, the bird suddenly moved, sliding his body away and blocking the attack with his wing.
The Crane swiftly defended itself from Chi-Nian attacks. The crane used to come back everyday to fight with her.
From the crane's attack and defence Chi-Nian derived her methods of defence and combined the way of the White Crane (female small step techniques) and Shaolin 18 Lohan Hands to create a complete system, Pai He Men.
The legend says that this crane was indeed a deity of Paihepai (White Crane Style) who descending to earth took form of a crane body to teach Chi-Nian its method.