The left part of the eastern wall is one of the most enigmatic sections of all paintings in the room.
To say it frankly: We have no idea concerning the meaning of these scenes...
Above, from left to right: a man sitting on a cube-like seat, in front of him two squatting semi-nude men. Then follows a horse with rider and probably the hind part of a second horse...
Above: Close-up of the left end of the eastern wall's left part. Between the man on the "cube" and the semi-nude males is a ball or disc. Along the bottom runs an ornamental register.
Possibly the pictorial contents of this left part of the eastern wall was bound up with the right part, although both are separated by the entrance to the hall.
Read about the right part of the eastern wall and an attempt of interpretation.