John Gill Commentary Psalms 135:11

"Sihon king of the Amorites, And Og king of Bashan, And all the kingdoms of Canaan," — Psalms 135:11 (ASV)

Sihon king of the Amorites, and Og king of Bashan
These are particularly named, because they were the first that were slain, and were the most mighty and powerful; see (Deuteronomy 3:11) (Amos 2:9) . These the Lord slew by the hand of Moses, a type of Christ; who has destroyed the god and prince of this world, that had the power of death, the devil; and has spoiled all his principalities and powers;

and all the kingdoms of Canaan ;
thirty one of them. These words explain the former; as the two kings mentioned point at the mighty kings slain, these kingdoms show who the great nations were that were smitten.