1 Kings 20:23 - Albert Barnes' Notes on the Bible

Their gods are gods of the hills - The local power and influence of deities was a fixed principle of the ancient polytheism. Each country was considered to have its own gods; and wars were regarded as being to a great extent struggles between the gods of the nations engaged in them. This is apparent throughout the Assyrian inscriptions. Compare also 2 Kings 18:33-35; 2 Kings 19:12. The present passage gives an unusual modification of this view. The suggestion of the Syrian chiefs may have been a mere politic device - they being really anxious, “an military grounds,” to encounter their enemy on the plain, where alone their chariots would be of much service. In the plain the Israelites had always fought at a disadvantage, and had proved themselves weaker than on the hills (see Judges 1:19, Judges 1:27, Judges 1:34).