The world of wuxia is almost exclusively a self-contained Chinese one, but DOMD features several European characters. Princess Sofia of Russia is the most prominent of these, but also in the story are two other historical figures of some note: Ferdinand Verbiest and Johann Adam Schall von Bell.
These two characters were Jesuit missionaries and also scientists/engineers who took jobs with the Qing imperial government, both under K'ang Hsi's father and K'ang Hsi himself. In DOMD, Verbiest and Schall von Bell were critical in supplying K'ang Hsi with the know-how to build cannon, which would be essential to K'ang Hsi's victory over Ng 3 Gwai's rebel forces.
DOMD is truly a turning point in the Jin Yong's universe in that it was the era when the trend began moving irreversibly away from a purely Sinocentric view to a global one, and wulin martial arts would give way to the weapons of science and technology; it was, for Jin Yong's universe, where the modern world began to assert itself.