1)
What is "b'Yar'ah"?
1.
Radak: This is a pronoun for Yerushalayim, i.e. the cities around it. It is compared to a forest regarding a fire - "k'Esh Teva'er Ya'ar" (Tehilim 83:15).
2.
Radak citing Targum Yonasan: In its cities.
3.
Malbim: It is on the south [of Yerushalayim]. From this side the city was conquered - "El Ya'ar ha'Sadeh Negev" (Yechezkel 21:2).
