Isaiah 13:1 The burden of Babylon, which Isaiah the son of Amoz did see.
Isaiah chapter 13 tells us what it is about. It is about the burden of BABYLON. And yet, as we continue reading the chapter, this is what is said:
Isaiah 13:9 Behold, the day of the LORD cometh, cruel both with wrath and fierce anger, to lay the land desolate: and he shall destroy the sinners thereof out of it.
10 For the stars of heaven and the constellations thereof shall not give their light: the sun shall be darkened in his going forth, and the moon shall not cause her light to shine.
11 And I will punish the world for their evil, ...
What does the "Day of the Lord," and punishing "the world for their evil" have to do with the burden of Babylon? Well, maybe the focus of the chapter changed after that opening statement about Babylon? Maybe God switched gears and isn't speaking about Babylon anymore.
Maybe---except we go on to read:
Isaiah 13:17 Behold, I will stir up the Medes against them, which shall not regard silver; and as for gold, they shall not delight in it.
18 Their bows also shall dash the young men to pieces; and they shall have no pity on the fruit of the womb; their eye shall not spare children.
19 And Babylon, the glory of kingdoms, the beauty of the Chaldees' excellency, shall be as when God overthrew Sodom and Gomorrah.
God stirs up the Medes against them. And according to Daniel chapter 5 it was the Medes and the Persians lead by king Darius/Cyrus that conquered Babylon and killed their king in one night.
The return reference to Babylon in these verses indicates that God has been speaking about that nation all along. And therefore the "burden of Babylon" is that it will experience the Day of the Lord's wrath and be punished for its evil. Therefore there is no other possible explanation except to understand that Babylon and the world are one and the same.