No tribe could go in and claim its own land. God was the one who said where the boundaries were. The boundaries were larger than what the Hebrews occupied.
Verses 13-15 – Moses fulfilled the task given to him, but the responsibility to carry out these instructions would fall to Joshua. The borders reflect the ideal territorial limits for the land of Israel, but was not fully realized until David and Solomon (2 Samuel 8:1-18; 10:1-9).