Kung Fu is a term used to refer to Chinese martial arts, also known as wushu and quanfa). The term kung fu can refer to any discipline or skill achieved through hard work and practice, not necessarily martial arts). The literal equivalent of "Chinese martial art" in Mandarin would be 中國武術 zhōngguó wǔshù). Kung Fu is a form of exercise, a means of self-defense, and an exchange of culture. It is also known as Gōng Fù (功夫), Wŭ Shù (武术) or Guó Shù (國術) . Kung Fu can be traced back to the Zhou dynasty (1111–255 BC) and even earlier. Its prescribed stances and actions are based on keen observations of human skeletal and muscular anatomy and physiology, and it employs great muscular coordination. The various movements in Kung Fu, most of which are imitations of the fighting styles of animals, are initiated from one of five basic foot positions. There are hundreds of styles of Kung Fu, and armed as well as unarmed techniques have been developed. Some examples of Kung Fu styles are Long Fist, Eagle Claw, and Taiji Quan. Kung Fu teaching emphasizes moral development as well as physical training, stressing values like respect, courage, tolerance, and reverence for life. The very nature of Kung Fu training is a long process of character building. Kung Fu is better than other forms of exercise for promoting health and fitness because it develops the inner faculties of vital energy and the mind. In modern times, Chinese martial arts have spawned the genre of cinema known as the Kung fu film. The films of Bruce Lee were instrumental in the initial burst of Chinese martial arts popularity in the West in the 1970s. Martial artists and actors such as Jet Li and Jackie Chan have continued the appeal of movies of this genre.