I found this on YourDictionary.com 
Yan·kee (yaŋ′kē) 
  
noun 
  
 
☆ a person born or living in New England
☆ 
a person born or living in a Northern State; Northerner
a Union soldier in the Civil War
[*]☆ a person born or living in the U.S. 
Etymology: < ? Du Jan Kees (taken as pl.) < Jan, John + Kees, dial. form of kaas, cheese; orig. (Jan Kaas) used as disparaging nickname for a Hollander, later for Dutch freebooter; applied by colonial Dutch in New York to English settlers in Connecticut 
  
Originally the Dutch had a small colony in New York 
I believe they called it New Amsterdam 
When the Brits took over they renamed it 
  
And as a Connecticut native in New England, I guess I'm 100% Yankee 
Never took it as Derogatory, in fact "Connecticut Yankee" is used here ...albeit a bit dated 
The South may have spoken it in anger, as the North said "Johnny Reb" 
But if someone's trying to kill you, it's not hard to understand name calling 
  
As far s the use of the term "Hun" 
Atilla the Hun was a fierce warrior who humbled the mighty Roman Empire 
If I was born a 1000 years from now & someone called us Yanks "Pattons" I don't think I'd mind 
My $.02