Deuteronomy 2

"The Emim had dwelt there in times past, a people as great and numerous and tall as the Anakim...the Horites formerly dwelt in Seir, but the descendants of Esau dispossessed them...That was also regarded as a land of giants; giants formerly dwelt there. But the Ammonites call them Zamzummim,  a people as great and numerous and tall as the Anakim...And the Avim, who dwelt in villages as far as Gaza." vv.10,12,20-21,23

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Do you remember about the nephilim?  Nephilim were descendants of the fallen angles that came down and had relations with women (Genesis 6).  They were all destroyed in the Flood but then there was another irruption of nephilim after (Genesis 6:4).  Many were called giants, Hebrew rephaim which most likely came from Rapha a well known descendant of the Nephilim.  So we still read of these people here in Deuteronomy with other names: Emim, Hornites, Zamzummim, Avim.  We first see of these people in Genesis 14 during the time of Abraham, "In the fourteenth year Chedorlaomer and the kings that were with him came and attacked the Rephaim in Ashteroth Karnaim, the Zuzim in Ham, the Emim in Shaveh Kiriathaim, and the Horites in their mountain of Seir."  This was Satan's scheme to destroy the line for the Messiah to come by mixed relations of fallen angles and women.  So why the Lord commanded Israel to utterly destroy these people to stop their lineage.  The Lord gave victory to these other nations of descendants of Lot, Esau and others so to destroy these giants, not just being Israel to destroy them.  
We don't have the nephilim or any form of them today, praise the Lord, but we still have Satan working trying to destroy the children of God.  How have you seen nonbeliever help destroy Satan's schemes that they don't even realize they're helping God's people out?