Numbers 31:37

37.And the Lord’s tribute of the sheep. The greatness of the victory is shewn by the result, since such an abundance of cattle could only have been collected from a wide and populous country. It is probable that it was not very fertile, and consequently only live stock, and not corn and wine, are enumerated as amongst their wealth. Still, we may conjecture that it was famous for pastures, since barren mountains could not have fed so many oxen, and goats, and sheep, and camels; besides, it is most evident, from the number of young women, that the men who were slain were more in number than their conquerors who had been sent to the battle; for suppose they each of them had an unmarried daughter, they would have almost three times outnumbered the 12,000 Israelites. Hence, again, it is manifest that the victory was effected by Divine power. It may, however, seem strange that, although the nation was almost destroyed, nevertheless their posterity existed some little time afterwards, as if new Midianites had been begotten from the ashes of their sires. For it was not a very long time that elapsed between this slaughter and the time of Gideon, when they again dared voluntarily to attack the Israelites, and in reliance on their multitude, to rush into the very heart of Canaan; nay, they had already brought all the neighboring nations into subjection. How this could have happened, since the Scriptures do not inform us, it only remains for us to make the conjecture, that many of them, as is often the case in a season of confusion, fled elsewhere, and soon afterwards returned into the land, which was now unoccupied. For the sudden irruption of the Israelites was like a storm which soon passed away; nor was flight a difficult thing for this unsettled and wandering nation. It might also have been the case, that many immigrants from various quarters flowed into the land, when stripped of its inhabitants; or even that the Israelites, having performed their work but slackly, sounded the recall sooner than they ought, and that God afterwards punished their remissness. At any rate, we are taught by this example that the wicked sprout up like foul and noxious weeds, so that, though often cut down, they soon cover the ground again.