"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:

https://www.godfire.net/eby/rev184.html