Some Ancient China links that might help

Population by Country:
https://www.cia.gov/library/publications/the-world-factbook/rankorder/2119rank.html

About the Mongols:
http://mongolianembassy.sg/about-mongolia/history/#.VkU3dmSrQ1i

http://www.newworldencyclopedia.org/entry/Mongol_Empire

http://www.allempires.com/article/?q=The_Mongol_Empire​

http://web.a.ebscohost.com/hrc/results?sid=e65abb14-0723-4733-b62a-1018653e17f3%40sessionmgr4002&vid=3&hid=4214&bdata=JmJxdWVyeT0mdHlwZT0wJnNpdGU9aHJjLWxpdmU%3d

​Yelu Ch’u-ts’ai:

http://www.britannica.com/biography/Yelu-Chucai

https://en.wikipedia.org/wiki/Yel%C3%BC_Chucai



http://go.galegroup.com/ps/retrieve.do?isETOC=true&inPS=true&prodId=GVRL&userGroupName=35sbo&resultListType=RELATED_DOCUMENT&searchType=BasicSearchForm&contentSegment=9781414422855&docId=GALE|CX2587200023


​http://www.metmuseum.org/toah/hd/shzh/hd_shzh.htm​