1)
What is the significance of people and animals not passing through?
1.
Malbim: It will be a dry desert; also flocks will not graze there.
2)
What is the significance of 40 years?
1.
Rashi: In Pharaoh's dreams, 42 years of famine were decreed. The dreams of seven [lean] cows and seven [bad] sheaves are each repeated three times. It says (a) what Pharaoh saw, (b) he told the dreams to Yosef, and (c) Yosef explained "the seven lean cows?" (Bereishis 41:27). Only two years were fulfilled then ? "Ki Zeh Shenasayim ha'Ra'av" (ibid. 45:6), and from when Yakov descended the famine ceased. They planted in the third year ? "v'Sen Zera? [veha'Adamah Lo Sesham" (ibid. 47:19). The remaining 40 were 'paid' now.
