(21) The Lord destroyed them before them.--It is noticeable that the conquest of Canaan is here brought into the domain of common history, by comparison with the conquests of gigantic races accomplished by Edom, Moab, and Ammon. The value of this analogy to Moses and Israel is plain. If the children of Lot, Ishmael, and Esau--who were but Gentiles, although they were Abraham's seed--were able to dispossess these gigantic races, how much more would Israel be able to dispossess the Canaanites under the personal guidance of Jehovah?

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.A people great and many, and tall as the Anakims,.... As the Emims were, Deuteronomy 2:10 but the Lord destroyed them before them; destroyed the Zamzummims before the children of Amman; or otherwise they would have been an too much for them, being so numerous, and of such a gigantic stature:

and they succeeded them, and dwelt in their stead; and in this way, and by these means, he gave them their land for a possession, Deuteronomy 2:19.