Hello Brian (and everyone else),
Transatlantic moving hasn't allowed me be online much but I'm surprised no one else has answered this one already. The three films you mention were adapted from the serialised novel _Marvelous Warriors of the Jianghu_ and subsequent follow-up works by Hunanese author Pingjiang Buxiao Sheng (lit. "someone from the insignificant Ping River.") The sobriquet is obviously a pen name--and, indeed, an ironic pun on the opening lines of the sixty-seventh chapter of Lao Tzu's _Tao Te Ching_--for Xiang Kairan (1889 - 1957) who started writing in the early 1920s.
Unlike most of his genre contemporaries, Xiang was actual martial artist himself and wrote both practical fighting manuals and treatises on martial arts. He studied abroad for several years in Japan and picked up considerable expertise on Judo, Kendo, and Geisha house culture. This augmented his own formidable knowledge on Chinese martial arts and tea house/opera houses. Due to such a thorough background, much of the conventions of the martial chivalry genre owe a considerable debt to Xiang's body of work, both fictional and non-fictional.
_Marvelous Warriors_ can be found on-line here (in simplified Chinese):
http://www.oklink.net/wxsj/other/jianghu/index.html If you prefer tangible books in Chinese, check out:
_The Representative Writings of Pingjiang Buxiao Sheng_ (Beijing: Huaxia Press, 1999) [ISBN: 7-5080-1794-3]
_Marvelous Warriors of the Jianghu_ (Changsha: Yuelu Publishers, 1986) [ISBN: 7-80520-090-4]