Excerpts from Books and Wikipedia
"Eventually Chinggis's grandson, Khubilai Khan, who reigned as chief of the Mongol world from 1260 to 1294, built his capital at Beijing. . . . He also had to cater to his Muslim constituency as defender of the faith; and for the Mongol followers of Tibetan Lamaism he had to be a Buddhist universal ruler. This diversity of faiths reflected the cosmopolitanism of the multiethnic Mongol world, where even Nestorian Christianity from Central Asia had its devotees within the ruling family. . . . In ruling China the Mongol's first problem was cultural. As full nomads from Outer Mongolia without much earlier contact with China, the Mongols were too different in speech, dress, customs, and background to bridge the cultural gap between themselves and the Southern Song Chinese. Being generally illiterate and comparatively few in number, in government they used West Asians (Uighur Turks, Arabs, even some Europeans like Marco Polo) and Sino-Ruzhen personnel of the conquered Jin empire. . . The Yuan era also saw a new attention to law as an antidote to arbitrary government." [Fairbank: China, p. 121-6] "The fall of the Yuan dynasty. Its remnants, known as Northern Yuan, continued to rule Mongolia. The breakup of the Mongol Empire, which marked the end of Pax Mongolica." [Wikipedia: Timeline of Middle Ages]