Actually this question opens up something we need to understand. The place and role of nations - in Gods eyes. Nations are important, and, part of the [end time] purposes of God is to reclaim the nations.
God’s intention was for nations. For the people to spread and divide. We see this after the flood. But, the people of the world rejected God. We see this at Babel. So, God gave ‘them’, the people, their desire, and gave them over. We see this in Deuteronomy 32. But more, he divided the people up into ‘nations’, set boundaries, and because they had rejected Him, He ‘put’ the nations ‘under’ the sons of god, who became these nations ‘gods’. We see evidence of this with Egypt, (Moses),and Babylon, (Daniel). Then we see Satan offering the nations back to Jesus in the temptation, because Satan knows that was one of the reasons Jesus came. (To reclaim the nations).
And, as well, we hear Jesus speaking parables about nations, sheep and goat nations. This relates to the end times, and ‘edges’ into the doctrine of the Millennium, so we’ll leave this here. (Although to get a full understanding of this question you will need to bring in your view of Revelation, and, not all ‘views’ will ‘fit’ this outline.)
Now, in Revelation we see the climax, the fulfilment of this. That is, ‘reclaiming’ the nations. But, those ‘over’ those nations aren’t impressed, and [those gods] have no intention of giving them up. Exactly the same as we saw with Egypt! Now, God Judges nations based on their leaders. We see this with Israel in the Old Testament. If they had a good leader/king, all went well, but if not, judgement came on them. So in Revelation, the ‘nations’ being angry is a reflection that the ‘leaders’ [leaders ‘motivated’ by their gods, just as pharaoh was] were angry.
Egypt, the nation (people) suffered under wrath, were the object of that wrath, [all] because of pharaoh, their leader, who was ‘motivated’ by the gods of Egypt. And, the same way the plagues were ‘put’ onto Egypt, will happen again during the Tribulation, thus invoking the response of those afflicted. (Nations).
So, that’s what’s being described in Revelation 11. “The nations were angry, and your wrath has come”.
REV 11:15 Then the seventh angel sounded: And there were loud voices in heaven, saying, “The kingdoms of this world have become the kingdoms of our Lord and of His Christ,