Historical Origins of Nagasaki, Omura, Shirakawago

I'm trying to do some research into the historical origins of Japanese
cities and villages, such as Nagasaki, Omura (near Nagasaki), and
Shirakawago in Gifu Prefecture. Specifically, I want to know when
these communities were formed. Information I've found on the Internet
is sketchy so far.

Thanks in advance.

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