The Canaanite king of Arad, who lived in the Negev, heard that the Israelites were approaching on the road to Atharim. So he attacked the Israelites and took some of them as prisoners.
Then the people of Israel made this vow to the LORD: "If you will help us conquer these people, we will completely destroy all their towns."
References for Numbers 21:2
The LORD heard their request and gave them victory over the Canaanites. The Israelites completely destroyed them and their towns, and the place has been called Hormah ever since.
References for Numbers 21:3