What’s more, both “how” and “ugh” may be attempts by white writers to represent the same word. That word is spelled hvo in Muskogee, where the letter v is a schwa (ə), like the a in English sofa. So it’s not hard to see how hvo was englished into “how.”
I could be wrong. Back in 1986, Cecil Adams of The Straight Dope argued for another group of American Indian languages. Someone had asked Adams whether Indians ever really used “how” as a greeting. He replied that no, they didn’t, but that in several Siouan languages of the Great Plains (Lakota, Dakota, and Omaha), there is a word that serves as “a sort of all-purpose introductory adverb or interjection.” That word is variously spelled ho, hao, hau, or howo.
The resemblance to Creek hvo, another multi-purpose affirmative interjection, is striking. Even though the Creek language is only distantly related to the Siouan languages, much like English is related to Persian.
Below: "A 1950s valentine derives humor from Indian stereotypes." (Credit: VintageValentineMuseum.com)