In the fifth aliyah G-d tells the Jewish people that when they cross the Jordan, they should drive out the inhabitants of the land and destroy their idols and occupy the land of Israel. And in this aliyah is the pussok: "If you do not drive out the land's inhabitants before you, those who remain shall be barbs in your eyes and thorns in your sides, causing you troubles in the land." This aliyah also contains a description of the boundaries of the land.