Describe the social changes in east Asia caused by the mongols?

They introduced Military rule.

They has four class system.

Explanation:

Mongols were able to rule east Asia by dividing it into four Khanates. There were Mongolians, Se mu, Nomadic, Asian Allies. They keep themselves on the top and it became difficult for other to come in their area and settle. They were able to maintain their rule and impose military laws in the area where they lived. By imposing peace they were able promote trades among other countries. They introduced and impose their own culture in the east Asia.  

a phrase from a poem by ralph waldo emerson about the battle of lexington and concord. emerson's words read, “here once the embattled farmers stood / and fired the shot heard round the world.”