This negative statement is used to emphasize their success in battle. This can be stated in a positive form. AT: "we were able to defeat the people of every city even if the city had high walls around it" (See: [[rc://en/ta/man/translate/figs-litotes]])
This is the name of a river that created the border between Sihon's land and the land of the Ammonites. (See: [[rc://en/ta/man/translate/translate-names]])