When Daniel told Nebuchadnezzar that he was the head of gold, it shows us a biblical principle that a king in prophecy represents the entire kingdom. In verses 39-40, "after you" indicates four successive world-ruling empires from the time of the Chaldean empire of Nebuchadnezzar until the return of Christ and the establishment of the Kingdom of God. We see in overview an outline of world history from a Gentile perspective, beginning with Nebuchadnezzar and coming all the way down through the various kingdoms until the image is struck on the foot by the Stone, representing the Kingdom of God, or Christ.
This prophecy brings us right into our present time—the time of the end—the time when can expect that the Stone, sometime in the not-too-distant future, will strike this image on the feet. We can look for that last empire, represented by the feet and toes, to exist today, or either be coming together, or will shortly be coming together. History has shown that these four empires, beginning with the head of gold, to be the Chaldean (the head of gold), the Medo-Persian (the chest and arms of silver), the Greco-Macedonian (the belly and thighs of brass), and the Roman (the legs and feet of iron) empires. The Roman Empire existed from 31 BC to AD 476. Secular history shows that the Vandals defeated Rome, but Rome was revived and re-established as "the Holy Roman Empire" under Emperor Justinian in AD 554.
John W. Ritenbaugh
Where Is the Beast? (Part 1)