What does "who dwelt in the land" mean?
Rashi #1, Rashbam and Targum Yonasan: They lived there originally until Eisav came [and captured the land from them].
Rashi #2: They were conversant with the ecology of the land - which area was good for planting olive-trees, and which for vines. And they were able to determine this by smelling the earth. 1
Which explains the name ?Chori? (from the word ?Meri?ach?). See also Ba'al ha'Turim.
Why do we need to know the lineage of Se'ir ha'Chori's family?
Ramban #1 (citing Rashi): Due to Timna, to teach us the esteem in which Avraham Avinu's family was held (Refer to 36:12:1:1).
Ramban #2 (citing Ibn Ezra): To draw a clear distinction between Se'ir and Eisav - seeing as Yisrael will later be warned against despising the Bnei Eisav and against taking their land.
Seforno: The Torah is listing here the names of the mighty warriors of that time, to teach us that by the will of Hashem, Eisav nevertheless succeeded in destroying them and taking over their land. 1
Peninim mi'Shulchan ha'Gra: All of these names are places. Since Eisav took them, Yisrael are forbidden to take them. 2
Ohr ha'Chayim: This teaches what Hashem gave to Eisav in the merit of his ancestors, even though he was a Rasha. We expound (Shabbos 85a) "Chori" - they became Bnei Chorin from their property (Eisav took it).
Malbim (to Divrei ha'Yamim I 1:38): Just like there are 70 Bnei Yaakov corresponding to the 70 nations, so there are 70 chiefs from Avraham's family - 13 from Yishmael and his sons, 13 from Bnei Keturah and their sons, 16 from Eisav and his sons, there were 26 chiefs from Se'ir, and 26 chiefs from Eisav stood in place of them; 3 and Amon and Mo'av.
As the Torah states in Devarim 2:22.
Surely, the Isur to take Eisav's land depends on what he owns at the time; Sichon's conquest of Amon and Mo'av permitted them to Yisrael! The Torah teaches us to assume that the owner of these lands is from Eisav, unless we know that later, someone else conquered them. (PF)
What is his source that each chief was replaced by one chief? The Torah lists below (36:40-43) 11 chiefs of Eisav who ruled [over everything that Eisav took from the Chori]! And why does he not count the 11? And even if one chief replaced each chief, perhaps some were among the 16 listed! (PF)
Who were Bnei Se'ir ha'Chori?
Ramban: ?ha?Chori? is the name of the founding father of the Chori tribe, 1 and Se?ir that of the country - which it adopted when Eisav (the ?Ish Sa?ir?) went to live there. 2
Ha'amek Davar: Se'ir ha'Chori was from Chivi ben Cana?an, like the Torah wrote earlier - in 36:2 "ve?es Aholivamah bas Tziv'on ha'Chivi" - and the Chori nation already existed in the days of Avraham. 3
Ramban: Which the Torah refers to in Devarim, 20:2.
The Ha'amek Davar proves that it was called ?Se'ir? before Eisav went to live there - See answer #2. Perhaps only the mountain was called ?Se'ir?, and it was only after Eisav arrived that they called also the country ?Se'ir? (PF). Alterntively, the Torah calls it ?Se?ir? in advance - since Eisav was destined to live there. Refer to 36:21:151:1.
As we find in Lech-L?cha, 14:6 - "ve?es ha'Chori be'Hareram Se'ir".
