John Calvin on Jeremiah 49:38

He confirms what I have just referred to as to their consumption; but he at the same time adds, that God would be in such a way the avenger as though his tribunal was erected in that land. He threatens that he would destroy the king and the princes; and this, as I have explained, was the consumption; for though some individuals would remain alive, yet the name of the people would not survive, the whole race as such would become extinct.

But these words ought to be noticed — that God would erect his throne. God is said to erect his throne when he rules; but his kingdom is not to be taken always in a good sense. God is properly said to rule or reign among the faithful, whom he governs by his Spirit. So God’s kingdom begins and has its origin when regeneration takes place. But sometimes, as I have already said, God is said to reign in the midst of his enemies, as we have seen respecting the Egyptians. He then erected his throne when he executed his recorded judgment on the Elamites, for though the Elamites were blind, yet God’s power was made really evident, and by the effect he proved that he was the King of that people whose wickedness he punished with so much severity. In short, as God is said to be silent, to sleep, or to lie down, when he does not execute his vengeance; so in this place he is said to erect his throne when he discharges the office of a Judge. It follows —

Jeremiah 49:39

39. But it shall come to pass in the latter days, that I will bring again the captivity of Elam, saith the LORD.

39. Et erit in posteritate dierum (hoc est, diebus sequentibus, vel successu dierum) convertam (vel, reducam) captivitatem Elam, dicit Jehova.