This speaks of the land that Yahweh gave to the Israelites as their inheritance. Alternate translation: "As you rejoiced when I made the land of the Israelites desolate" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Possible meanings are 1) I will make your land desolate" or 2) "I will rejoice when your land is desolate" or 3) "I will make other people rejoice because of your desolation."
# Then they will know
The word "they" possibly refers to 1) "the people of the earth" or 2) "the people of Israel and Judah."