Disillusioned JW:
I am an atheist (and thus I believe there is no such thing as divine inspiration) and as a result of my research I lean towards the belief that the book of Daniel was written in the 2nd century B.C.E (about the year 164 B.C.E.), but I am not certain it was written then. Furthermore, I think that the second kingdom referred to in Daniel chapter two is Media-Persia instead of Media; that the third kingdom referred to is Greece (and its subsequent break up, in stages, into the the Ptolemaic and Seleucid kingdoms) instead of Persia; and that the fourth kingdom is Rome (whether in the form of the Republic of Rome, the Roman Empire, or a combination of both).
The ‘silver’ kingdom is actually much more likely… Babylon. Daniel explicitly says the ‘gold’ kingdom is not simply Babylon, but specifically Nebuchadnezzar, and that the kingdom after him would be inferior. The ‘copper’ kingdom is Persia (only religious people say Medo-Persia and Media-Persia is only slightly better). Then Greece (‘iron’), then the divided kingdoms including the Seleucids and Ptolemies (‘clay/iron’). Even if it were possible, there is no reason the author of Daniel would refer to the fall of the ‘Roman empire’ that didn’t even exist yet, which is a religious superstition only, especially Daniel 11 is very clearly all about events only up until Antiochus Epiphanies IV.