John Gill Commentary Deuteronomy 2:21

"a people great, and many, and tall, as the Anakim; but Jehovah destroyed them before them; and they succeeded them, and dwelt in their stead;" — Deuteronomy 2:21 (ASV)

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) .