Daidō (大同) was a Japanese era name (年号,, nengō,; lit. "year name") after Enryaku and before Kōnin. This period started in May 806 and ended in September 810. During this time, the emperors were Heizei-tennō (平城天皇) and Saga-tennō (嵯峨天皇).
| Daidō | 1st | 2nd | 3rd | 4th |
|---|---|---|---|---|
| 806 | 807 | 808 | 809 |
| Preceded by: Enryaku |
Era or nengō: Daidō |
Succeeded by: Kōnin |