All their cities wherein they dwelt. — Better, all their cities in their dwelling-places. This expression is explained by a reference to Joshua 13:21, from which it appears that the five kings or chiefs of the Midianites who are mentioned in Numbers 5:8 dwelt in the territory which Sihon, king of the Amorites, had wrested from the Moabites. The Midianites were a nomad people, and were not likely to have built cities for themselves.
Related Commentaries of Numbers 31:10
Numbers 31:10
10 And they burnt all their cities wherein they dwelt, and all their goodly castles, with fire.