This might conceivably explain why General Tso's Chicken is very much an overseas Chinese dish, filtering the hot, peppery taste of Hunan cuisine, through the sweetening process of Cantonese cooking. Most of the immigrants to America came from coastal regions: Shanghai and Canton.
...General Tso's chicken recipe may be no more ancient than 1972, and may have more in common with Manhattan than with mainland China. On "The Definitive General Tso's Chicken Page" (www.echonyc.com/~erich/tso.htm) New Yorker Eric Hochman theorizes "It was invented in the mid-1970s, in NYC, by one Chef Peng.
"Around 1974, Hunan and Szechuan food were introduced to the city, and General Tso's Chicken was an exemplar of the new style. Peng's, on East 44th Street, was the first restaurant in NYC to serve it, and since the dish (and cuisine) were new, Chef Peng was able to make it a House Specialty, in spite of its commonplace ingredients."
My own research led me to the same city, but a different Manhattan restaurateur, who claims the dish is the brilliant invention of his former partner, a gifted Chinese immigrant chef named T.T. Wang.
"He went into business with me in 1972," said Michael Tong, owner of New York's Shun Lee Palaces, East (155 E. 55th St.) and West (43 W. 65th St.). "We opened the first Hunanese restaurant in the whole country, and the four dishes we offered you will see on the menu of practically every Hunanese restaurant in America today. They all copied from us...