Neijia is a term in Chinese martial arts, grouping those styles that practice neijing, usually translated as internal martial arts, occupied with spiritual, mental or qi-related aspects, as opposed to an "external" approach focused on physiological aspects. The distinction dates to the 17th century, but its modern application is due to publications by Sun Lutang, dating to the period of 1915 to 1928. Neijing is developed by using neigong, or "internal exercises," as opposed to "external exercises" (wàigong ),