Historically, the art of Baji Quan/Pigua Zhang was employed by the imperial bodyguards. Although relatively well known among military personnel, serious martial artists, and indoor disciples of Liu Yunqiao (1909-1992), it was not available to the public. Liu, serving at the highest level of security at the palace, founded the Wudang Martial Arts Development Center with the goal of making traditional Northern Chinese martial arts more widespread. Through the emigration of his disciples, including Tony Yang, by the late 1970s and early 1980s the style had spread throughout the North and South America, Europe, and the Far East. Yang and Figler discuss three phases of training, apparatus such as the dog skin for hand training, and the principles related to body structure, coordinated power, breathing, and stomping. A detailed pictorial sequence illustrates Liu Da Kai (Six Big Openings), a set of six moving postures designed to train both long-range bridging and short-range striking.