.Developed in the late 1800s by founder Dong Hai-chuan, the "Eight Diagram Palm" martial art, in Chinese,ba gua zhang, is also written baguazhang, pa-kua chang, and abbreviated as ba gua or bagua. Ba gua is the only martial art specifically designed for simultaneous defense against multiple opponents. Since Sun Lu-tang's books that were popularized in the 1920s, ba gua has traditionally be said to belong to the "internal martial arts" (nei jia quan / nei-chia ch’üan (内家拳) ).  The "internal martial arts" are often described as offering a distinct class of training, where qi (also written ch'i ) internal energy, along with "softness," or subtle technique is prioritized over gross strength or raw physical power. [ADD LINK TO DISCUSSION ABOUT THE "SOFTENING" OF T'AI-CHI AND THE HISTORY OF "INTERNAL MARTIAL ARTS."]