嵯峨将东寺交予空海

Emperor Saga entrusted Tō-ji to Kūkai in 823. The temple already stood near the eastern side of Heian-kyō's southern gateway; it was not a new foundation built for Kūkai. The grant gave his esoteric Buddhist community a court-supported place for teaching, ritual, and construction within the capital.

Kūkai organized the temple around his religious program, with the lecture hall as a central setting for its images and worship. Mandalas, represented through diagrams and arrangements of sacred figures, made the teaching visible. Construction required continuing court and monastic support, materials, and skilled work. The lecture hall was completed in 839, four years after Kūkai's death.

Later fire destroyed the original hall, and the present lecture hall dates to its reconstruction in 1491. Tō-ji's continuity therefore lies in the community, its worship, its site, and some surviving objects as well as in buildings of different dates. The 823 grant began a new institutional use of an existing temple, not the completion of the entire complex now seen there.