What is the meaning of "Ad Atah"?
Which time-period is the Torah referring to?
Rashi: It refers to the fourteen years after they entered Eretz Yisrael. 1
Oznayim la'Torah: The Pasuk is referring to three time-periods: "Va'avartem es ha'Yarden" refers to the fourteen years after Yisrael crossed the Yarden; "Viyeshavtem ba'Aretz", to the era of Mishkan Shiloh, and "Veheni'ach lachem mi'Kol Oyveichem ... ", to the er of the Beis-Hamikdash. 2
What is the definition of "Menuchah" and "Nachalah" respectively?
Rashi: "Menuchah" refers to Mishkan Shiloh, during which period Bamos were forbidden, and "Nachalah", to Yerushalayim. 1
Hadar Zekenim and Da'as Zekenim: "Menuchah" is when Hashem will give them respite. "Nachalah" is when they cross the Yarden (to inherit Eretz Yisrael).
Targum Yonasan: "Menuchah" refers to the Beis-Hamikdash - the place of rest and "Nachalah" to 'the inheritance of land.
See Sifsei Chachamim. Torah Temimah, citing Zevachim, 119a: To permit Bamos from the time they arrived in Gilgal until the Mishkan was built in Shiloh and from the time that Shiloh was destroyed until the Beis-Hamikdash was built in Yerushalayim. See Torah Temimah, note 33.