Probably upon the king of Babylon's first invading Judah many fled, and more as he went on in his conquests, overrunning the country, and it is likely at the taking of the city many escaped, and fled into several countries as they had opportunity, or judged this or that country would be safest; some fled to Moab, some to Ammon, some to Edom, some one way, some another. But when they heard that the king of Babylon had set a governor of their own religion and country over them, they came back to him; and there being few people left in the land, which was of itself wonderfully fruitful, they gathered a great plenty of grapes and other summer fruits which the country produced.
Related Commentaries of Jeremiah 40:12
Jeremiah 40:12
12 Even all the Jews returned out of all places whither they were driven, and came to the land of Judah, to Gedaliah, unto Mizpah, and gathered wine and summer fruits very much.