In 809, Emperor Heizei assigned his throne to Emperor Saga, and moved to Heijo-kyo (the ancient capital of Japan in current Nara) as the Retired Emperor Heizei.
大同(日本)4年（809年）、平城天皇が嵯峨天皇に譲位し、平城上皇として平城京に移り住んだ。