Which defunct countries still have valid passports [closed]

Background: I need a list of countries which still have valid passports attached to them for a project. I don't know, what to do about countries that no longer exist, however.

Which defunct countries' passports are still valid? That is in the hypothetical situation that a passport was issued on the day a country became defunct when will the last passport for that country become invalid?

Defunct country here means:

country was annexed or formed a union with another one (e.g. the German Democratic Republic joined the Federal Republic of Germany)
or country broke up into constituents (e.g. the Soviet Union or Czechoslovakia)
or a simple country name change (e.g. Zaire to Democratic Republic of the Congo or F. Y. R. of Macedonia into North Macedonia)

Situations like Yugoslavia (most other republics leaving the federation) or Ethiopia (independence of Eritrea) can likely be ignored count as there is a clear main successor state which carried/carries on the name.

Are there instances, where the passports became invalid instantly? I.e. none of the successor states accepted the old passports for any length of time as a travel document.

Otherwise, I assume that passports could just stay valid until their validity at the date of issuing expires.

Edit regarding the meaning of passport validity for this question: The passport must be usable as a travel document.

Please also disregard countries which are/were never (nearly) universally accepted (Abkhazia, South Ossetia, Transnistria, Kosovo, Western Sahara, etc.) or which have again undecided status (Taiwan/RoC). This is not about the political question of recognizing countries as independent.

passports

Best Answer

In general, if a country accepts another country's passport it is implicitly acknowledging the existence of that country. This is why sometimes the use of passports is a big issue in international relations.

The poster example would be the issues between the People's Republic of China and the Republic of China (Taiwan). You may travel from one to the other, but you cannot use a passport of one to enter the other, because officially they do not recognize each other. A citizen of one of those countries will use instead a "travel permit" that works like a passport but is not called a passport so it does not imply official recognition.

So you could say that, as long a country A accepts your "defunct" country B's passports, country B is not actually defunct (at least from country A's POV).

Of course, if the desapparition of the country is recent and sudden, maybe you will have many citizens of that country that only have the "old" passport, and for a time it can be exceptionally accepted on practical grounds. And usually the new country that succeeds it will hurry up to issue its own documents (if needed, just by stamping some seals on the old passports) to make it the new situation clear.