The dream of King Nebuchadnezzar in Daniel 2 is widely regarded as the historical template describing 4 Gentile Empires that follow one another and ultimately lead up to the stone (not cut by human hands) that smashes the feet of this final kingdom. This is followed by the establishment of the Kingdom of God - that fills the earth. (Img. 1)

https://www.bible.com/bible/111/DAN.2.31-35.niv

statue.jpg, Oct 2021

Daniel himself identifies King Nebuchadnezzar or the Babylonian Empire as the head of gold. Dan 2:39 (Img. 2)

babylon.jpg, Oct 2021

The rest of the parts of the statue are not identified by name in this chapter. But I believe it's possible to deduct from history the identity of the three remaining parts of the statue.

The breast and arms of silver is believed to be the Medo-Persian Empire under King Cyrus - This empire was comprised of the combination of the former Median and later Persian Empires (2 arms of silver). (Img. 3)

medo-persia.jpg, Oct 2021

The belly and thighs of bronze is believed to be the Greek or Macedonian Empire. This started out as a single empire under Alexander the Great (belly of bronze). But upon his death, his kingdom was divided among several generals, with two of those generals becoming dominant (thighs of bronze) -  Ptolemny to the South (Egypt) and Seleucus to the North and East. (Img. 4)

greece.jpg, Oct 2021

There are differences of opinion regarding the identity of the 4th kingdom - the legs of iron which then lead up to the feet of iron mixed with clay. Most common is the belief that the Roman Empire occupies this slot. The uninspired headings in many Bibles even suggest this. The problem with this theory is that the Roman Empire essentially ended in the 5th century. There is the belief that a final iteration of this empire will re-emerge in its final form - feet of iron mixed with clay.

Another problem in assigning this 4th kingdom to the Roman Empire is the geographic area that it covered. The first 3 empires (Babylonian, Medo-Persian, and Macedonian) were mostly eastern - east of the Mediterranean and extending to Babylon and beyond. Remember this dream was given to King Nebuchadnezzar of Babylon. The Roman Empire was centred around the Mediterranean and extended west and north all the way up to Britain. It never really conquered all the territories formerly occupied by the first three kingdoms. (Img. 5)

rome.jpg, Oct 2021

The other problem lies with the nature of this 4th kingdom. It was supposed to be "different" from the others. It "devoured and crushed" those that were before it (Dan 7:7). Many argue that the Roman Empire, though powerful, could not be described as being much different than those before it. It is a well established fact that the Roman Empire, and those before it, "tolerated the customs and religious practices of peoples brought under their control". 

The alternate theory to the identity of the 4th kingdom is the Islamic Caliphate. Though this kingdom appears well after the Macedonian kingdom, it still meets the criteria of coming after. In addition, the territories conquered cover the same geographic areas as the 3 previous kingdoms. (Img. 6) 

caliphate.jpg, Oct 2021

This kingdom was also "different" and did display a "devouring" and "crushing" nature. While there were periods where the caliphs would "tolerate" the customs and religions of conquered people. There were also periods where they would order the destruction of properties like the Church of the Holy Sepulchre, churches, synagogues, torah scrolls and other religious artifacts. This was one of the pre-cursor events that led to the crusades. This was also the practice of our modern day ISIS during their reign of terror. But like the Roman Empire, a Caliphate does not currently exist - though political Islam is the dominant influence in the region today. And there have been repeated calls for the establishment of an Islamic Caliphate today by some of the more radical Islamic states (eg. Turkey).

Joel Richardson makes a strong case for this 4th kingdom arising from the Middle-East in his book "Mideast Beast - The Scriptural Case for an Islamic Antichrist"

https://joelstrumpet.com/wp-content/uploads/2019/02/Islamic-Antichrist.pdf