The development of the Japanese sword closely parallels events in Japanese history. The broad divisions of each are noted here. The specific historical eras are referred to as “nengo” and are named after the emperor of the period. The sword eras have separate notations: Koto refers to the “old sword period”; Shinto refers to the “new sword era”; Shinshinto is the “new, new sword era”; Gendai or Kindai is the “modern sword era” while Shinsaku refers to newly made swords.
NOTE: Exact dates may vary in different texts since Japanese eras (nengo) do not exactly match Western calendar years. References will differ on the dates of the division between Shinshinto and Gendai. Some authors date from the Meiji Reformation of 1868 while others date from the Haitori Edict of 1876 which banned the wearing of swords and eliminated the samurai class.