Albert Barnes Commentary 2 Chronicles 20:20

"And they rose early in the morning, and went forth into the wilderness of Tekoa: and as they went forth, Jehoshaphat stood and said, Hear me, O Judah, and ye inhabitants of Jerusalem: believe in Jehovah your God, so shall ye be established; believe his prophets, so shall ye prosper." — 2 Chronicles 20:20 (ASV)

Tekoa (2 Samuel 14:2 note) was located on the border of the desert that skirts the highlands of Judea to the east. The town was built on a considerably high hill.