Couting Coup and Counting Ponies
The Warrior illustrated in the piece is capturing the ponies, thus gaining honor, and attacking his enemy without striking his enemy physically.  This feat is referred to by most main stream scholars and the public as “horse stealing”.  To this warrior, it was an act of taking the enemies sacred companions to leave him disabled and afoot. It's also widely known among the tribes that the same horses that were stolen could be taken back by that same tribe or another enemy tribe.  The two ponies running are colored red and blue to represent Heaven and Earth, and trailing them is a Warrior carrying a coup staff in full regalia riding a bobtailed yellow pony. The yellow horse is a sacred color for the Arikara, as it represents the South and their deity, Mother Corn.