 In this way, the Emperor accomplished a return of grace or baoen, repaying Zhang's act in life with posthumous reward affecting his afterlife.Tombs M1 (in the west) and M2 (in the east) house matching subterranean burial structures of Zhang Boya and his wife, with mounds rising 10 and 7.5 meters respectively above the ground.The tombs share the same basic building techniques, structure and shape.