In Ezra 6:22, should it not be the King of Persia instead of Assyria, as the temple was completed during the reign of Persia? Perhaps I have missed out on something. -- John Louis (Singapore)

It happens a few times in the OT (as in the Apocrypha) that the name of a former dominion is used even after the empire ruling it has fallen.

Asshur (Assyria) can be viewed as a territory, even after conquered by the Babylonians (in the late 600s BC) and then the Persians (the 530s). Another example is Nehemiah 13:6, where Artaxerxes is called the king of Babylon... The Persians ruled (former) Babylon.

I guess it would be like referring to Zimbabwe as Rhodesia, or the US as the (British) Colonies. People would know what you meant, even if the phraseology is a bit unusual.