Albert Barnes Commentary Numbers 31:10

"And all their cities in the places wherein they dwelt, and all their encampments, they burnt with fire." — Numbers 31:10 (ASV)

Goodly castles - Rather, this refers to hamlets, both here and in (Genesis 25:16). The word is derived from טוּר (ṭûr)—signifying “a row” or “range” . It probably indicates those collections of rude dwellings, made of stones piled one on another and covered with tent-cloths, which are used by the Arabs to this day. These dwellings are also frequently mentioned as douars in narratives of the French campaigns in Algeria. They would usually be formed in a circle. See the word “Hazeroth” in (Numbers 11:35).