Research is a process that takes TIME. Start early and do a little bit each day. You will NOT have a thesis statement after one day in the library. You need to learn a little bit about your topic before you can develop an argument!
"Portrait of Kublai Khan by Anige." National Palace Museum, Taipei, Taiwan/Wikimedia Commons. Ancient and Medieval History Onlines. Facts On File, Inc. http://www.fofweb.com/activelink2.asp?
Here's a list of selected specialized reference books (available in the Garver Room) you may want to consider: