1)
Why does the Torah discuss the generations of other nations, e.g. Edom?
1.
Da'as Zekenim: It is to make known Seder Olam (chronicles).
2.
Moshav Zekenim (to Bereishis 43:7): Yisrael may not take land of Edom, so we must know who is from Edom. 1
1
So R. Yehudah ha'Chasid answered a challenge to his assertion that among any three [consecutive] verses, we learn Halachos, Isur or Heter. Also refer to 41:1:153:1.