Generally, there were two major factors that led to the decline of the Yuan Dynasty: one was the class conflict caused by the heavy taxation, the other one was the ethnic contradiction resulting from the 'Four Class System'. ... Also, power struggles within the ruling class became more and more serious.
This would have to be A. By my research. Sorry if it's wrong. Have a good day!
To gain more resources to aid industrialization.
The arrival of the Indo-Europeans in the Near East made huge changes in the region with long lasting effects. After their arrival, the region started to develop significantly, multiple strong empires were formed, empires that were developing the sciences, the weapons, the culture, politics, empires that managed to spread all of these things around and change the way of thinking and functioning of the whole region, and later on, on a much larger scale.
