Mining in the soft alluvial soil would have been dangerous work, especially as the town ditch was deep and supplied with abundant water from the Euphrates.
Cyrus, had he failed in his night attack, would probably have at once raised the siege; and Babylonian independence might perhaps in that case have been maintained down to the time of Alexander.
Even thus, however, the "Empire" would not have been continued.

So soon as it became evident that the Babylonians were no match for the Persians in the field, their authority over the subject nations was at an end.
The Susianians, the tribes of the middle Euphrates, the Syrians, the Phoenicians, the Jews, the Idumseans, the Ammonites and Moabites, would have gravitated to the stronger power, even if the attack of Cyrus on Babylon itself had been repulsed.

For the conquests of Cyrus in Asia Minor, the Oxus region, and Afghanistan, had completely destroyed the balance of power in Western Asia, and given to Persia a preponderance both in men and in resources against which the cleverest and most energetic of Babylonian princes would have struggled in vain.

Persia must in any case have absorbed all the tract between Mount Zagros and the Mediterranean, except Babylonia Proper; and thus the successful defence of Babylon would merely have deprived the Persian Empire of a province.
In its general character the Babylonian Empire was little more than a reproduction of the Assyrian.

The same loose organization of the provinces under native kings rather than satraps almost universally prevailed, with the same duties on the part of suzerain and subjects and the same results of ever-recurring revolt and re-conquest.