State an old period of time

[Selorm Aglagoh]

I just want to know how to state a very old period of time, specifically the 900s
I'm doing a presentation on Kendo and I'm trying to speak about the advent of the Katana

I want to say "Dating back to the 900s...."
But all I can really think of is 九百年前のなか...

 

[Angel Valis]

You can say "the 900s" with 九百年代 / 900年代 (ねんだい) or "the 10th century" with 十世紀 / 10世紀 (せいき).

 

[TokubetsuHero]

Thanks!

 

[Majestic]

I think maybe 10世紀 would be better than 900年代 . I'm sure both would be equally understood, but 900年代 feels a bit odd to me (I am not a native speaker though).

Another option would be Heian Jidai (平安時代). Which might be more relevant to a native speaker, or to a student/enthusiast of Japanese history (although its a bit more ambiguous given the length of time represented by the Heian period).