1)
What are the implications of "ha'Hu Nikra Eretz Refa'im"?
1.
Rashi, R. Bachye and Rashbam: It implies that the land of Og Melech ha'Bashan is the land of the Refa'im that Hashem gave to Avraham (at the B?ris bein ha?Besarim - Rashbam [but not the lands mentioned earlier in the Parshah, even though they were also called 'Eretz Refa'im']). 1
2.
Ramban: The Torah is simply saying that they took possession of the entire area specified, which 2 was all called the land of the Refa'im. 3
2
Ramban: As if it had written "asher Hu Nikra Eretz Refa'im" - as we find in Divrei ha'Yamim 1, 26:28 and in Ezra 10:17.


