The first kingdom historically and biblically is Babylon. Who was the first king of Babylon?

The Assyrian king Nimrod.

"And the beginning of his kingdom was Babel, and Erech, and Accad, and Calneh, in the land of Shinar."(Gen 10:10) The other version states that Nimrod is the first king who rule over all human on earth, no one before him is ever mentioned as a king.

Most students of the Bible know him from the story of Nimrod and the tower of Babel.  When God confused the languages Nimrod’s name changed to reflect the different languages.  In his book, The Giza Discovery, author Peter Goodgame has done a masterful job of laying the foundation of who this guy was to the ancient world... and who he will be in the days ahead. The Bible calls him Nimrod, but to the ancients he was known as: Gilgamesh, Baal, Melqart, Adonis, Eshmun, Dumuzi, Dionysus, Bacchus, Orion, Mithra, Apollo, Ra, Tammuz, and Osiris.  Other scholars have linked Maitreya with Nimrod/Osiris/Ashur.

And Cush begat Nimrod: he began to be a mighty one in the earth. He was a mighty hunter before* the Lord: wherefore it is said, Even as Nimrod the mighty hunter before the Lord. Genesis 10:8-9 * Strong's Concordance. nekach: before, over against. (He obviously was against the Lord).

The Bible describes Nimrod as mighty.

(Before the flood). There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.

Giants?  Goliath was a giant, whom David fought.  Besides Goliath, the Holy Bible mentions many giants;

“…all the people that we saw in it are men of a great stature.  And there we saw the giants, the sons of Anak, which come of the giants: and we were in our own sight as grasshoppers, and so we were in their sight. Number 13:32-33

That also was accounted a land of giants: giants dwelt therein in old time; and the Ammonites call them Zamzummims; Duet. 2:20. 

 These giants had six fingers and six toes;

And yet again there was war at Gath, where was a man of great stature, whose fingers and toes were four and twenty, six on each hand, and six on each foot: and he also was the son of the giant. 1 Chronicles 20:6

And there was yet a battle in Gath, where was a man of great stature, that had on every hand six fingers, and on every foot six toes, four and twenty in number; and he also was born to the giant.  2 Samuel 21:20.

So the angels had children with human women and as a result, some of their offspring were a strange race of giants and had six fingers and six toes.  The early people called these  angels gods.

“…And there are seven kings, five are fallen, and one is, and the other is not yet come; and when he cometh, he must continue a short space. And the beast that was, and is not, even he is the eighth, and is of the seven, and goeth into perdition. Revelation 17:10-11.

The angel is saying that five kings have already come and gone, one was at the time John was alive and another one was coming.  To sum it up there will be seven kings total and the eighth king will be one of the seven. If you go back to what the angel Gabriel told Daniel, he said, “…the great horn (the false Christ) that is between his eyes is the first king.” 

In Revelation, the false prophet orders an image made of the false Christ who was killed by a sword and yet lived, “… It ordered them to set up an image in honor of the beast who was wounded by the sword and yet lived.” Revelation 13:14.

There are several different theories and texts on how Nimrod was killed but they all have one thing in common, he was murdered by a sword.

This end time prophecy has not happened yet; "And this man (the Messiah) shall be the peace, when the Assyrian shall come into our land: and when he shall tread in our palaces, then shall we raise against him seven shepherds, and eight principal men. And they shall waste the land of Assyria with the sword, and the land of Nimrod in the entrances thereof: thus shall he (the Messiah) deliver us from the Assyrian, when he cometh into our land, and when he treadeth within our borders." (Micah 5:5-6, KJV).

So we come full circle from the first kingdom city of Babylon with the Assyrian as the first king  to the last kingdom city Babylon the Great invaded by the Asssyrian.