Good points Larry - I think one of the other commenters brought up the film too. I'll be sure to check it out!

While Japan did close itself off entirely - it also saw them regress signficiantly from a martial perspective.

270 years of relative peace under the Tokugawas saw Japanese warriors give up firearm technologies (notably the musket), and dismantle thousands of defensive structures and forts.

By the time Commodore Perry sailed into Tokyo Bay in the 1850s - Japan had become a technologically backward nation.

Only their rapid industrialisation, and the focus of European powers elsewhere saved the after this time.