It's easier than building the cities...

Deuteronomy 19:7 says, "Wherefore I command thee, saying, Thou shalt separate three cities for thee.  19:8 And if the LORD thy God enlarge thy coast, as he hath sworn unto thy fathers, and give thee all the land which he promised to give unto thy fathers;"  I guess invading people and taking their city is easier than building your own cities.  I just don't understand how god let these squatters build anything on land he promised the Israelites.  Seems like poor planning on gods part.  That is unless he wanted these people who he made but doesn't love just to make the cities for his favorite people.