In the iconography of Han tombs,the widespread Han belief in and rituals for yin-yang union and the mating of the dragon and the tiger is preserved in pictorial language.This is the basis for the belief in immortality obtained by collecting one’s essence by "refining the body in the underworld" in the tomb or "body refining palace," as recorded in the Lao Zi Xiang’er Zhu(老子想爾注)of the Eastern Han Dynasty.It is also the foundation for the belief that one could become immortal through dragon and tiger mating,shedding the dead body as discussed in Zhou Yi Can Tong Qi(周易參同契).As the intermediary that invites the mating of the dragon and the tiger,the cinnabar field,tripods and other Taoist symbols in the solemn tomb-palace are the vehicle for the process of concentrating the essence in mating in the "Purple Palace of the Great Oneness" (太一紫房).The Can Tong Qi,that combines well-developed Book of Changes school of the Han dynasty,the Way of the Yellow Emperor and Lao Zi(黃 老 道),and the belief in shedding the body to become immortal,illuminates the mating of the dragon and the tiger through the principles of the Book of Changes.The Can Tong Qi and these Han tomb paintings give strong support to each other.To conclude that the original version of the Can Tong Qi and Cinnabar Field theory took shape in the Eastern Han Dynasty is solidly grounded on the beliefs of the day