I am unable to identify the original background, but I imagine it has been heavily darkened in contrast to the campfire which provides the sole source of illumination to the scene. The First Nations characters are enjoying a meal and some are lighting their pipes. Two of them are facing away from the central group, to observe the captive, staked out on the ground.
One holds a stick with a glowing ember to light his pipe, and this improves his view of the captive's face. Her body is already marked, and there may be worse to come. We are seeing very good use of light and shade here, to convey an atmosphere of fear, tension anticipation.