And they utterly destroyed all that was in the city, both man and woman, young and old, and ox, and sheep, and ass, with the edge of the sword. 6:21
Trivia: In Joshua 10, what did Joshua tell his captains to do to the five captured kings?
This verse says that Ai was never again occupied after it was destroyed by Joshua. But Nehemiah (7:32) lists it among the cities of Israel at the time of the Babylonian captivity. 8:28
God promises to give Joshua all of the land that his "foot shall tread upon." He says that none of the people he encounters will be able to resist him. But later we find that God didn't keep his promise, and that many tribes withstood Joshua's attempt to steal their land. 1:3-5, 3:10, 15:63, 16:10, 17:12-13, 17:17-18, 21:43-45