The history and culture of sacred trees incorporated into the State rituals in ancient Northeast Asian states was explored. The ritual and precinct of the Sajik of Joseon dynasty, were analyzed from the perspective of sylvanism, the reverence of grandiose tall tree and forest. Institutionalized sylvanism comprised sylvanic tree, precinct, rituals, and mode of thinking. Dan‐tree represents a sacred tree tradition that has been institutionalized into the ritual and precinct in the Manchuro‐Korean region, while Sa‐tree that of China Proper. Dantree was the sylvanic tree in the Dangun narrative and institutionalized in the mythical kingdom of Dangun Joseon. However, Dan‐tree in the Dangun narrative was depicted in some Koguryo mural paintings. Dan‐tree is a fruit‐bearing broadleaved tree species and it appears to be Manchurian walnut (Juglans manschurica). A special bow made of Dan‐wood was produced by the Ye people. Koguryo and its preceding kingdom (Biryu) had the sylvanic precincts at least before the 1st century BC, which were equivalent to the Sajik precincts in China Proper. The roles of Dan‐tree and its precincts of Later Joseon appear to have inherited into Hahn's sodo in the midland and southern part of Korean peninsula. Sa‐tree contains different tree species in ancient kingdoms in China Proper. It was pine (Pinus massoniana) for the mythical Xia, cypress (Platycladus or Thuja orientalis) for Shang (Yin), and chestnut (Castanea mollisima) for Zhou. Sa‐institution contains tree species, precinct, rituals, and mode of thinking. It incorporated Jik, the crop god, during the Zhou period. The succeeding kingdoms and empires in China Proper maintained the Zhou tradition (Sajik) with the priority of Sa over Jik. The sylvanic mode of thinking and the precinct landscaping in the Manchuro‐Korean tradition are embedded at the base of the royal Sajik precinct of Joseon dynasty and the Great Sajik Ritual conducted by modern Koreans. A culturalist strategy was established for transforming the ancient values of sylvanic trees into some modernized environmental and cultural values. The culturo‐natural legacy of the sylvanic trees and forests are the cultural capital available for forest and environmental conservation and afforestation in Northeast Asia. And they can also be subjected to the relevant development of environmental history and forest philosophy.
