Sforno on Deuteronomy 4:47/ספורנו על דברים ד׳:מ״ז

1ויירשו את ארצו, they inherited his country after having conquered land that had been inhabited, suitable for settlement. This land would offer the opportunity to observe all of G’d’s commandments in it. They would not need to fear invaders, etc. This is where Moses began his review of the Torah and his speech of warning the people of the importance of remaining loyal to G’d.