"Among the very instructive and deeply significant illustrations given by the Holy Spirit in the visions of John we have the beautiful presentation of the conquest of Babylon by the “kings of the east.” The historical backdrop is, of course, the conquest of ancient Babylon by the two kings from the east, Cyrus of Persia and Darius of Media. In the book of Revelation we first meet these “kings of the east” at the time of their anointing as kings in chapter seven. “And after these things I saw four angels standing on the four corners of the earth, holding the four winds of the earth, that the wind should not blow on the earth, nor on the sea, nor on any tree. And I saw another angel ascending from the east, having the seal (kingly authority) of the living God: and he cried with a loud voice to the four angels to whom it was given to hurt the earth and the sea, saying, Hurt not the earth, neither the sea, nor the trees, till we have sealed the servants of our God in their foreheads” (Rev. 7:2-3)."
"John is still wondering what the four angels holding the four winds can mean when he sees the four mighty sentinels all at once turn their eyes to the east. And behold, another messenger comes ascending out of the east as the morning sun comes, announcing God’s new day. He comes clothed with light as with a garment; the widespread earth shines bright under his glory; and his voice is as the sound of many waters. The ascending messenger holds in his hand the seal of the living God! And, addressing himself to the four mighty sentinels, he speaks to them with a voice that they hear above all the commotions that arise from the earth, and the tempests that rage in the sea, saying to them that they are commanded not to hurt the earth, nor the sea, nor the trees, until “we” have sealed the servants of our God in their foreheads."
Much more in the link:
"Let us then consider that the drying up of the waters of the Euphrates is for one purpose — that “the way of the kings of the east might be prepared.” Ah, the “way” of the kings, the road, the path, the highway, is being PREPARED. There is a preparation! God is making ready a road, a way, a means for the entrance into the earth of the kings of the east, the kings of the sunrise, the kings bringing the dawning of a new day — the sons of God. These sons are coming spiritually from the east — not out of eastern mysticism or New Age philosophies — but right out of the shining glory of the Lord! But notice what had to happen before they make their appearance — a road must be prepared. The preparation of the road indicates a clearing away of obstacles, rocks, trees, rubbish; the raising up of low places, the cutting down of high places, so that the way is made straight with no obstacles, barriers, hindrances, or impediments of any kind. Can you, dear one, think of any obstructions in your life that would hinder the manifestation of sonship in the fullness of the glory of the Lord? Do you need encouragement, do you need correction, do you need deliverance, do you need greater faith or purity, do you need more perfecting, change, and transformation — the faithful dealing of God in these areas bespeaks the preparation of the “way” of the kings of the east! Let God have His way that you may have part in this glorious manifestation of His sons!"