Knights Lose their Titles and "Dexterity"
"It is not proper for a noble to be an innkeeper." -- Royal ordinance cited in a lawsuit. (quote from Barbara Tuchman's "A Distant Mirror")
The word for "knight" in most languages suggests a horseman. Even in English the word "dexterous" is related to the French word for a war horse... destrier (DIS-tree-ear). It means the horse walking at the knight's right side. A knight rarely rode his war horse except in battle. Instead he rode another horse with his war horse led by a squire at the right. But maintaining two horses and a squire is expensive. When it gets too expensive one can expect a knight to lose his title as he finds other ways to make money. Approximately 50% of the noble families who had a title at the beginning of the century will be struck from the roles by the end of those 100 years... often due to economic reasons.  
The Numbers are In. The People are Gone
The census this year estimates the population of China to be 65 million. That is about HALF of what it was in 1200. The Black Death has taken its toll along with the rebellion that overthrew the Mongols. The Ming Dynasty is off to a good start but it will be many years before they will get those numbers back. Given their limited resources right now, they can take their time. They need a way to feed those people first.  
No More Backsliding Allowed
The Iberian peninsula (modern day Spain and Portugal) has become a very bad place for Jews at this time and it's only going to get worse. Last year riots left of 10,000 Jews dead and many were forced to leave or convert to Christianity, seeing it as the only way to avoid death. In order to prevent any backsliding, the Jews are prevented from associating with unconverted Jews or living in the same places where they once lived. The expulsion of the Jews from Spain won't occur until 1492. 
This Year on Wikipedia
Year 1393, Wikipedia.
- Tuchman, Barbara Wertheim. (Barbara Tuchman, bio). A Distant Mirror: The Calamitous 14th Century. Ballantine, 1979. p. 16-18. (BOOK) quote="A squire belonged to the nobility by birth whether or not he obtained the belt and spurs of a knight, but legal process was often required to determine what other functions a gentleman might undertake without losing noble status. Could he sell wine from his vineyard, for instance?"
- Alex Shrugged Note: I am pulling a lot of information from a single source here and I don't want anyone to think this is solely my idea about the horses and dexterity. That is Barbara Tuchman's idea. I found the information interesting so I'm relating it to you here but there is a reason Barbara Tuchman is a popular historian. She writes well and chooses good subjects.
- Richard III (play) - Wikipedia, 2014 [last update]
- Black Death in Asia: Bubonic Plague, Kallie Szczepanski, About.com.
- McClellan III, James E. (James McClellan bio) & Dorn, Harold et al. Science and Technology in World History: An Introduction. JHU Press, Apr 14, 2006. p. 119. (BOOK)
- 1393: The Muzaffarids, by Timur, ExecutedToday.com, 2010-May-22.
- 1393, from Jewish History. (TIMELINE) quote="1393 August 18, KING JOHN I (Spain) - In an effort to prevent 'backsliding' by converted Jews, he prohibited them from living in the same quarter as unconverted Jews or even eating with them."
- Ralph Peters interviewed on Fox News "Hannity," 2014-Jul-22.