The Seven Trumpets
Revelation 8
To recapitulate, after the Lamb (Jesus) took the scroll from the Father in Rev 5, the angels began to open the seven internal seals in Rev 6.
Revelation 9:1-12
In Rev 8 the first four trumpets brought about the collapse of the western third of the Imperial Roman Empire, shown in red. The Eastern Empire remained Roman.
Revelation 9:13-21
And the sixth angel sounded, and I heard a voice from the four horns of the golden altar which is before God, 9:14, saying to the sixth angel which had the trumpet, Loose the four angels which are bound in the great river Euphrates.