Numbers 21:1 - Joseph Benson’s Commentary on the Old and New Testaments

The armies of Israel now begin to emerge out of the wilderness, and to come into a land inhabited; to enter upon action, and take possession of the frontiers of the land of promise. King Arad Or rather, according to the Hebrew, and all the ancient versions, The Canaanitish king of Arad; for Arad was not the name of a man, but of a city or territory, Judges 1:16; and he seems to be called a Canaanite in a general sense, as the Amorites and others. Which dwelt in the south Of Canaan, toward the east, and near the Dead sea. By the way of the spies For though the spies, whom Moses had sent thirty-eight years before, then went into Canaan, and returned unobserved, yet their coming, and their errand, it is likely, were afterward known to the Canaanites, gave them an alarm, and obliged them to keep an eye on Israel, and get intelligence of their motions. The Seventy, however, and others, take the word Atharim, which we render spies, for the name of a place. Took some of them prisoners God permitting it for Israel's humiliation, and to teach them not to expect the conquest of that land from their own wisdom or valour.