1. What is a Nengō?
A nengō (年号, era name) is a dating system based on the reign of Japanese emperors. Swords inscribed with a nengō indicate the exact year of production.
2. Format of a Nengō Inscription
A typical date inscription follows this pattern:
- Era Name + Year + Month + Day
- Example: 永正五年二月日 (Eishō 5 Nen 2 Gatsu Hi)
- Translation: “A day in February of the 5th year of Eishō (1508).”
3. Examples of Nengō Used on Swords
Some common nengō found on swords:
| Era Name | Years Active | Example of Nengō on a Sword |
|---|---|---|
| 天正 (Tenshō) | 1573–1592 | 天正十八年 (Tenshō 18, 1590) |
| 慶長 (Keichō) | 1596–1615 | 慶長三年 (Keichō 3, 1598) |
| 元禄 (Genroku) | 1688–1704 | 元禄八年 (Genroku 8, 1695) |
| 享保 (Kyōhō) | 1716–1736 | 享保十三年 (Kyōhō 13, 1728) |
Swords dated with a nengō inscription are highly valuable for historical research and authentication.