The Horims also dwelt in Seir - The whole of this verse was probably added by Joshua or Ezra.

The Horims also dwelt in Seir before time,.... Which is the name of a mount, and so of the country, from it; so called from Seir the Horite, who dwelt in it before it was possessed by Esau and his sons; but who the Horim or Horites were, from whence they had their name, is difficult to say; they were as early as the times of Chedorlaomer, Genesis 14:6. They seem to be so called from their dwelling in holes and caves in rocks, which the southern part of Edom or Idumea was full of, and to be the same the Greeks call Troglodytae:

but the children of Esau succeeded them; Esau and his sons marrying among them, made way for getting the country into their possession, as appears from Genesis 36:2 and in which they afterwards settled themselves by the dint of sword, since it follows:

when they had destroyed them from before them, and dwelt in their stead; even in Seir where they had dwelt, afterwards called Edom, from one of the names of Esau, Genesis 36:8.

as Israel did in the land of his possession, which the Lord gave unto them; because this is said before the Canaanites were drove out of their land, and it was possessed by the Israelites, some think this was written by Ezra, or some other hand; but there is no need to suppose that; Moses, by a spirit of prophecy, and in faith of the promises and prophecies of God relating to this affair, which were just now about to be fulfilled, might write this; besides, it may refer to what was already done to the kingdoms of Sihon and Og, kings of the Amorites; which had been taken from them, and given to the tribes of Reuben and Gad, and the half tribe of Manasseh; and the above instances as well as this may be observed, to encourage the people of Israel that they should succeed in dispossessing the Canaanites, and settling in their land, in like manner as dispossessions of this kind had already been made.

The origin of the Horites (i.e., the dwellers in caves) of Mount Seir, who were driven out of their possessions by the descendants of Esau, and completely exterminated (see at Genesis 14:6, and Genesis 36:20), is altogether involved in obscurity. The words, "as Israel has done to the land of his possession, which Jehovah has given them," do not presuppose the conquest of the land of Canaan or a post-Mosaic authorship; but "the land of his possession" is the land to the east of the Jordan (Gilead and Bashan), which was conquered by the Israelites under Moses, and divided among the two tribes and a half, and which is also described in Deuteronomy 3:20 as the "possession" which Jehovah had given to these tribes.

The Horims also dwelt in Seir beforetime; but the children of Esau succeeded them, when they had destroyed them from before them, and dwelt in their stead; as Israel did unto the land of his possession, which the LORD gave unto them.

2:12 Which the Lord gave - The past tense is here put for the future, will give after the manner of the prophets.

succeeded: Heb. inherited

stead: or, room

2:8-23 We have the origin of the Moabites, Edomites, and Ammonites. Moses also gives an instance older than any of these; the Caphtorims drove the Avims out of their country. These revolutions show what uncertain things wordly possessions are. It was so of old, and ever will be so. Families decline, and from them estates are transferred to families that increase; so little continuance is there in these things. This is recorded to encourage the children of Israel. If the providence of God has done this for Moabites and Ammonites, much more would his promise do it for Israel, his peculiar people. Cautions are given not to meddle with Moabites and Ammonites. Even wicked men must not be wronged. God gives and preserves outward blessings to wicked men; these are not the best things, he has better in store for his own children.