Before his death, Moses had commanded Israel to set up stones with the Law on them on Mt Ebal.  Six tribes were to stand on Mt Gerizim and proclaim the blessings of obedience, while the other six were to stand on Mt Ebal to pronounce the curses on disobedience (Deut 27).  "God was giving the people a huge object lesson:  what happened to them in the land was going to depend...on whether they wre living on Mount Gerizim or Mount Ebal" (Schaeffer, p. 121).  

         

After the defeat of Ai, Joshua gathered the people on Mt Ebal to build an altar and to read the entire law publicly (Josh 8:30-35).  Most interesting is the mention of the presence of aliens. These were the descendants of the "mixed multitude" that came out of Egypt, plus additions gained during the years in the wilderness.
    
The presence of these non-assimilated outsiders during the invasion of Canaan makes it very clear that God's judgment on Canaan was very specific in target and limited in scope.  Despite the rigidity of Israelite life and the innumerable rules, there was room in this theocracy for like-minded people who were not direct descendants of Jacob. This, more than Rahab, constitutes a grace note to what was a cruel and bloody period in Israel's history.