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