I was going to comment on the 'administration' point yesterday but ran out of time. We, of course, are not talking about democratically elected governments and presidents. This was a military invasion, conquest and take-over. One ruler out; new ruler in. The Bible says Belshazzar (acting ruler) was killed. Secular sources say Nabonidus was captured. Pfft. That was the end of the Babylonian administration.
Indeed. My initial analogy about the change of the US president was only a very basic demonstration of a different administration. My follow-up suggestion of a take-over by a foreign power was more accurate.
The Nabonidus Chronicle indicates that Cyrus arrived in Babylon about 16 days after his armies took it and he was readily accepted by the people - they hadn't thought much of Nabonidus anyway. Quickly, and within the same month (Month 8), new officials had been appointed. Beginning in Month 9 (so before the year 539 BCE was out), he was reversing previous Babylonian policy, starting to return the gods to their cities and temples. Obviously, the Jews didn't have gods in their temple, so it would be the sacred temple utensils which would have to be returned to them.
Anyway, point being, Ethos's contention about how long ("several months") it would take for Cyrus to get some real authority and power to change policies, and get a new administration together, etc. is NONSENSE! He's the conquering king, for crying out loud, he can do what he damn well likes, and he DID, as history shows!
The thing is, even if Cyrus' had decided, "they ran things really well here, I don't need to change any policies," it was still a new administration as 539 quite definitely marked the end of the Neo-Babylonian empire.