The cut hemp rope around the throat of the bay stallion indicates that, until a few moments previously, the animal had belonged to someone else. The hip brand denotes that this former owner was a White man. The Cheyenne, doubtless one of a party of horse raiders, is establishing his ownership of the animal by touching it with the lashes of his Mexican braided-rawhide quirt.
In the confusion of a raid it was always an early priority to establish which animals belonged to each man. This was done by being first to touch them, in front of witnesses, precisely like counting coup. Perhaps there was some dispute over ownership of this horse. Arrow's purpose in this drawing---exactly like witnessing a deed of ownership---is to offer his testimony concerning the new owner. Compare this composition with Plates 112 & 160, in which the same man, wearing the same spotted shirt, and riding the same white horse, is engaged in capturing other animals. This man is Arrow's Nisson comrade---see the discussion with Plate 112. Here, he is armed probably with a Remington rolling-block carbine. Compare the visible details of this weapon with Arrow's complete depiction of the firearm in Plate 5.