Is the Mongol Yuan massacre a true story, or is it a slander by foreigners?

Mongolian massacre is true, there are a lot of materials are so recorded. The Mongols were nomads, and the way they invaded a place in the early days was as long as the land, not the people, so the massacre was the easiest way to take in the power. They not only massacred a large number of Jin, Xixia and other ethnic minorities, but also the Han Chinese of the Song Dynasty, before and after the killing of tens of millions of lives. When with their aggression expanded to the scope of Europe, Central Asia, the massacre also followed, bringing not civilization is not progress, but the civilization of the development of the overall stagnation.