1919: Ann Little (prolific silent screen movie star) said that her first work was in westerns where: "Indians scalped defenseless pioneers an burned them at the stake with the utmost freedom."

From an 1919 article titled, Why I went into the Movies and how I got in, (Muncie Evening Press), Ann Little, age 28 and star of many silent screen hits such as "Custer's Last Fight" (1912), "The Invaders" (1912), The Lieutenant's Last Fight (1912), and The Squaw Man  (1914) - Ann Little explains some of her work early in her career:

 "My first work was in Western two-reelers, which were all the rage at the time to the exclusion of pretty nearly everything else. It was the dime novel stage of the screen. All the Deadwood Dicks and Wild Bills or the yellow-back stories found their way to the movies by devious paths and under assumed names. Indians scalped defenseless pioneers an burned them at the stake with the utmost freedom."

1919, Sep 1  Muncie Evening Press 

An example of the burning at the stake scene - from The Invaders, starring Ann Little: 

Being burned at the stake, though I can find very little events on-line, and honestly, there are far more whites burning blacks than ever a Native tribe or person burning a poor white settlers... and yet, this exits. It's repeated over and over. Even the Order of the Red Men reenact these burning at public festivities  and private initiation ceremonies, plus plays, wild west shows and, of course, dime novels meant for children.

1919, Sep 1 Muncie Evening Press