Matthew Poole and continuators on Jeremiah 49:31

31 Arise, get you up to the wealthy nation that dwelleth without care, saith the LORD, which have neither gates nor bars, which dwell alone .

The supposed result of Nebuchadnezzars counsels, giving charge to his Armies to march against the Kedarens, which lived at ease and quiet, and took no care. That had no Cities, nor Gates, nor Barrs to keep their Enemies out, nor were near any Neighbours that could assist them, nor very near to one another living in Tents, so might easily be overrun, and conquered, and made a prey to Enemies.

Marginal references: Or, the nation that is at ease.