In the sketch "Hannibal, Missouri" (1852) Twain discusses Native Americans in the familiar noble savage mode. In "The Noble Red Man" (1870) Twain takes quite a different tone, offering an extremely vitriolic and negative portrayal of NA Indians. There are also passages of *Roughing It* that depict NA Indians. The incomplete "Huck Finn and Tom Sawyer Among the Indians" is the fullest and most direct fictional treatment I know of--its tone, like most of Twain's work on NA Indians, echoes "The Noble Red Man." Other places where NA Indians appear in some semblance or other include "The Extract from Captain Stormfield's Heaven" (as denizens of heaven), in *Life on the Mississipi* (Schoolcraft Legends), in "The Dervish and the Offensive Stranger" (some discussion of wrongs done to NA Indian culture), and, of course, in the form of Injun Joe in *Tom Sawyer*. Twain also sometimes uses NA Indians for analogical purposes (usually negative) in works like *Innocents Abroad* and the sketches "A Day at Niagara" (1869) and "The Pah-utes"(1862). I don't know that this list is exhaustive, but I hope it helps. Best, Mike Hurst