As well as the point made by Tartanwizard above, it's also the case that the word "nation" is sometimes used for groups of people rather than for geographical areas - for example, the Cherokee, Chickasaw and other native American nations.
The book 'Registration plates of the world' includes both the current nations and their past statuses. They have a website http://www.europlate.org
I'm sure they can fix it up to see it.