How about a broader view?
Revelation 17:7-13
King James Version (KJV)
7 And the angel said unto me, Wherefore didst thou marvel? I will tell thee the mystery of the woman, and of the beast that carrieth her, which hath the seven heads and ten horns.
We are told the seven heads and ten horns are to be explained.
8 The beast that thou sawest was, and is not; and shall ascend out of the bottomless pit, and go into perdition: and they that dwell on the earth shall wonder, whose names were not written in the book of life from the foundation of the world, when they behold the beast that was, and is not, and yet is.
9 And here is the mind which hath wisdom. The seven heads are seven mountains, on which the woman sitteth.
10 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.
A total of seven Kings for the seven Mountains.
Five are fallen: Egypt, Assyria, Medo-Persia, Babylon, and Greece.
One is: Rome.
The other is not yet come: the Empire the Anti-Christ rules, though he is not the first ruler, the seventh King is.
11 And the beast that was, and is not, even he is the eighth, and is of the seven, and goeth into perdition.
He is of the seventh Kingdom/Empire, but arises to take the Kingdom (and I place this as likely at the mid-point of the Tribulation.
12 And the ten horns which thou sawest are ten kings, which have received no kingdom as yet; but receive power as kings one hour with the beast.
These are not in power at the time of the writing, just as the Seventh Kingdom is not yet arrived (which makes it unlikely that Rome, which was in power at the time can be considered). Their rule is limited to a short time.
They support the base authority that is the Beast from which the seven heads arise/arose:
13 These have one mind, and shall give their power and strength unto the beast.
God bless.