Apparently when asked "who are those Indians" (lakota/sioux). The crow scouts chuckled and replied to the officer that they are "Sioux". In Crow, Sioux means "snake in the grass". I shall continue to use the term Sioux, because it is widely understood , but we should use "Lakota".
Lakota were the western most but there were also Dakota and Nakota. And I thought Sioux meant 'enemy'.