I just wanted to point out a couple of other lines of evidence to show that Nebuchadnezzar never conquered or desolated Egypt and that he was not the ruler of the whole of the known world.
Firstly Nebuchadnezzar II was famous for his building work in Babylon, including the hanging gardens. Something else he built was called the Median Wall. This wall was to the north of Babylon and stretched between the Tigris and Euphrates rivers. The Greeks believed this wall to be 100 feet high. The point is that this was a defensive wall to keep out the Medes from the north. Although Nebuchadnezzar had formed an alliance with this kingdom he realised that the Medes were becoming stronger and were becoming a threat to him. An alliance does not mean he ruled over the Medes and the wall proves he was fearful of an attack.
Herodotus mentions that the Babylonians mediated the peace between Media and Lydia after the battle of the eclipse in 585BCE but does not say that Nebuchadnezzar ruled these nations.
There are many archaeological and historical lines of evidence that show that rather than being made desolate by the Babylonians, the Egyptians under the Saite dynasty from Psammeticus I to Amasis were very prosperous. We can date the lengths of rule of these pharoahs using Apis bull stelae and death stelae. These give the lengths of the reigns of the first four pharoahs of the Saite dynasty as follows:
Psammeticus I - 54 years; Necho II - 15 years; Psammeticus II - 6 years; Hophra - 19 years.
Herodotus and Manetho both give the lengths of reigns of Amasis and Psammeticus II as 44 years and six months respectively. These lengths of reigns are also confirmed by various Persian documents and inscriptions.
According to the bible this 40 year desolation could not have happened until after the reign of Hophra. 2 Kings 24:7 shows that in the reign of Necho II Nebuchadnezzar had only conquered as far as the Egyptian border, and Jeremiah 44:30 says that Hophra (who was still ruling) would be given into the hands of his enemies.
So is there any evidence for a Babylonian conquest of Egypt during the reign of Amasis. After Amasis siezed the throne from Hophra there was a period of great prosperity and peace in Egypt. Numerous business documents have been discovered which show the prosperity enjoyed by Egypt at this time. To curb excessive wealth private individuals were encouraged to donate land to temples. These transactions are recorded in donation stelae.
Although the Egyptians no longer tried to expand eastwards, their sea trade and naval expeditions expanded much further than Syria. Herodotus and Diodorus comment extensively on this period. Diodorus says that Cyprus was captured during the reign of Amasis and Herodotus speaks of treaties between Amasis and Croesus of Lydia (Histories I.77) and Polycrates of Samos (Histories III.39). There are also many surviving records from Egyptian naval commanders who served under Hophra and Amasis.
There is a fragmentary text that shows a campaign by Nebuchadnezzar in his 37th year against Amasis but the objectives are uncertain being described as 'remote territories amid the sea'. Maybe this was to combat Egypt's growing influence in the eastern Mediterranean. But as yet not one inscription has been found in Egypt showing Nebuchadnezzar ruling.