In Jin Yong's world, the Mongol Empire's rise to power was accompanied by an increasing number of wulin martial artists on the empire's payroll. Their beginnings were modest: Genghis Khan started out with NO wulin martial artists in his service at all. He finally acquired the services of an elite martial artist when Gwok Jing returned from his adventures in China to serve as a commander in the Mongol army, but even though Gwok Jing was the seventh most powerful known martial artist in the world at the time, Genghis valued Gwok Jing for the latter's leadership abilities, not his martial arts. Gwok Jing's individual martial arts skills, good as they were, were not of great value to Genghis' goals. Gwok Jing was the only wulin martial artist that served the Mongol Empire, however, during Genghis Khan's lifetime.
By ROCH, the Mongols had beefed up their roster of martial arts agents considerably. At one point in ROCH, the Mongols had the Golden Wheel Monk, Fok Do, Dat Yee Ba, Wan Hak Sai, Siu Seung Tze, Lui Mor Singh, Ma Gwong Jor, and (briefly) even Yeung Gor and Little Dragon Girl at their service. The Golden Wheel Monk was a Greats level fighter, and several of the others were known to be the equal of or superior to the senior members of the Cheun Jen Sect. That was a formidable roster, although it was completely decimated by the end of ROCH.
In HSDS, the Mongols seemed to build their wulin representation through various outsider groups and mainstream wulin rejects. There were no Greats level fighters serving the Mongols at this time, but the likes of Sing Kwun, the Yeun Ming Elders, Ah Dai, Ah 2, and Ah 3 was each superior to the members of Shaolin's Hung-generation monks and the Mo Dong 7 Heroes. The roster of wulin martial artists serving the Mongols was also longer than it had previously ever been, because there were dozens of anonymous martial artists serving alongside the aforementioned experts. Although the Yuan Dynasty lacked a martial artist at the level of the Golden Wheel Monk, they did have Tibetan fighting monks at their service, and the combined power of these monks proved capable of overwhelming even Cheung Mo Gei.