John Wesley on Joshua 15:14

Drove thence - That is, from the said territory, from their caves and forts in it. These giants having either recovered their cities, or defended themselves in the mountains. Three sons of Anak - Either the same who are mentioned, Numb 13:33, and so they were long - lived men, such as mainly were in those times and places: or their sons, called by their father's names, which is very usual.