"C. was overthrown by invading Mongol tribes in A.D. 1279" would be the best phrase describing China's Song Dynasty, but this was of course not always the case.
Answer: The speed of cultural diffusion
The emergence of the internment has made several things which are not possible before become possible. There are so many cultures on earth that would have never had any contact with one another but for the emergence of the internet. Through this avenue, one can learn so many things from other cultures without leaving one's location.
Explanation:
Universities grew up around cathedrals, and courses of study helped educate clergy. ... They supplied observers with information about European Christian beliefs.