It was in 1206 that Genghis Khan began to make arrangements for a projected invasion of China, and by 1214 he was master of all the enemy's territory north of the Yellow River, except Peking.

He then made peace with the Golden Tartar emperor of northern China; but his suspicions were soon aroused, and hostilities were renewed.

In 1227 he died, while conducting a campaign in Central Asia; and it remained for his vigorous grandson, Kublai Khan, to complete the conquest of China more than half a century afterwards.

So early as 1260, Kublai was able to proclaim himself emperor at Xanadu, which means Imperial Capital, and lay about one hundred and eighty miles north of modern Peking, where, in those days known as Khan-baligh (Marco Polo's Cambaluc), he established himself four years later; but twenty years of severe fighting had still to pass away before the empire was finally subdued.

The Sung troops were gradually driven south, contesting every inch of ground with a dogged resistance born of patriotic endeavour.