This is the second effect John describes from the seismic shifts God generates in the thinking of those influenced by the spirits of the air. There were many nations and peoples and languages on earth in John’s day, all having cities (= many people living together for mutual benefit) of various sizes and strengths. These cooperations of people disintegrated, collapsed, fell as a result of God’s wrath being poured out onto the air.
19 The great city was split into three parts, and the cities of the nations fell, and God remembered Babylon the great, to make her drain the cup of the wine of the fury of his wrath.