These full color pictures originated in China in the 12th century during the Sung Dynasty. The herder is you.  You are the person on the spiritual quest.  The ox represents the mind. This particular model of the "Ten Ox herding Pictures" has its roots in the Pali commentaries which state,

"Just as a man would tie to a post a calf that should be tamed, Even so here should one tie one's own mind tight to the object of mindfulness."