'Hills' in the Bible

Then the king of Aram's servants said to him, Their god is a god of the hills; that is why they were stronger than we: but if we make an attack on them in the lowlands, we will certainly be stronger than they.

And a man of God came up and said to the king of Israel, The Lord says, Because the Aramaeans have said, The Lord is a god of the hills and not of the valleys; I will give all this great army into your hands, and you will see that I am the Lord.