As Yahweh commanded Moses his servant, so did Moses command Joshua: and so did Joshua; he left nothing undone of all that Yahweh commanded Moses.
Perhaps these were the older more influential towns that previous generations had rebuilt on their former ruins. [Note: Keil and Delitzsch, p. 122.] If this is the meaning, probably Joshua did not burn them because he wanted to preserve these towns with time-honored sites for the Israelites’ occupation.