LEGEND OF THE CONDOR HEROES started a chain of events that would take numerous twists and turns over the course of next 150 or so years and directly affect the lives of hundreds of characters. By the time a reader/viewer reaches the end of HEAVEN SWORD & DRAGON SABRE, a look back reveals a very long and winding road spanning the entire rise, peak, and fall of the Mongol Empire in China.
But the structure of the CONDOR HEROES TRILOGY provides a fascinating symmetry at its beginning and end...and one wonders if Jin Yong didn't consciously plan the trilogy that way.
In LOCH, the first significant martial art we are introduced to is the 9 Yum White Bone Claws, practiced by Chan Yeun Fung and Mui Chiu Fung. After 9 Yum White Bone Claws, numerous other martial arts are introduced in LOCH, ROCH, and HSDS...but 9 Yum White Bone Claws did not figure much in LOCH after the deaths of Chan Yeun Fung, Mui Chiu Fung, and Yeung Hong...and was never even mentioned in ROCH. It would have been very easy to simply forget that this martial art even existed by the middle of HSDS, but surprise: 9 Yum White Bone Claws makes an unexpected reappearance at the end of HSDS as Chow Chi Yerk's martial art...long, long after all of its practitioners in LOCH were dead and after not being even alluded to in ROCH.
In LOCH, the primary romantic conflict existed among a young Han Chinese man (Gwok Jing), a young Han Chinese woman (Wong Yung), and a Mongolian princess (Hua Jeng). In the end, the Han Chinese man chose the young Han Chinese woman, leaving the Mongolian princess to take up a monastic life. No parallel relationship existed in ROCH, but in HSDS, a young Han Chinese man (Cheung Mo Gei) chose a young Mongolian (Chiu Mun, though technically a Uighur, was nevertheless a member of the Mongolian aristocracy) woman over a Han Chinese woman (Chow Chi Yerk), who also chose a monastic life. Doubly ironic is that Chow Chi Yerk, as member (and Leader) of the Ngor Mei Sect, was in some ways the heir of Wong Yung's father, East Heretic Wong Yerk See (the Ngor Mei Sect was founded by Gwok Seung, Wong Yerk See's granddaughter who was known during her youth as "Little East Heretic")...and Chiu Mun, of course, was an indirect heir to the lineage of Genghis Khan (and thus, Princess Hua Jeng).
Finally, LOCH depicted the founding of the Mongols' empire in China, with the rise of Genghis Khan and his conquest of the Hsi Hsia Kingdom and the Jin Empire, while HSDS depicted the Mongols' Yuan Dynasty in its final throes before being overthrown by the native Ming Dynasty. Here, there is an irony in that Gwok Jing, the hero of LOCH, was a subordinate of Genghis Khan, the Mongol conqueror of China, while Cheung Mo Gei, the hero of HSDS, was the superior of Chu Yeun Cheung, who would expel the Mongols and become the founder of the Ming Dynasty.
In some ways, HSDS seemed to have been written as a bookend with LOCH...almost like LOCH in reverse.