Seven nations Ten are mentioned, Genesis 15:19; but this being some hundreds of years after, it is not strange if three of them were either destroyed by foreign or domestic wars, or by cohabitation and marriage united with and swallowed up in the rest.
Related Commentaries of Deuteronomy 7:1
Deuteronomy 7:1
1 When the LORD thy God shall bring thee into the land whither thou goest to possess it, and hath cast out many nations before thee, the Hittites, and the Girgashites, and the Amorites, and the Canaanites, and the Perizzites, and the Hivites, and the Jebusites, seven nations greater and mightier than thou;