"Single combat fought on horseback"
A single combat between two samurais on horseback. Swords were only used by warriors on horseback when they had no or almost no choice. In the picture, the samurais have already used their bows and are now sword fighting. Both of them are wearing a horo attached to their backs. A horo is a rigid cloak protecting the wearer from arrows and it often marked the wearer as a person of noble birth.