How do we know that Babylon in Revelation is symbolic of a Global system?

"The sixth angel poured out his bowl on the great river Euphrates and

something happens. 

Q: What do the waters represent? 

A: Revelation 17 tells us it represents peoples, multitudes, nations, and tongues,

--So if the river is symbolic, that must mean that Babylon that sits on the river must also be global and symbolic." 

Stephen Bohr