'Hill country' in the Bible

Then Abijah stood on Mount Zemaraim, which is in the hill country of Ephraim, and said, “Jeroboam and all Israel, hear me.

When Asa heard these words and the prophecy of Azariah son of Oded the prophet, he took courage and removed the detestable idols from the whole land of Judah and Benjamin and from the cities he had captured in the hill country of Ephraim. He renovated the altar of the Lord that was in front of the portico of the Lord’s temple.

Jehoshaphat lived in Jerusalem, and once again he went out among the people from Beer-sheba to the hill country of Ephraim and brought them back to Yahweh, the God of their ancestors.

He also built cities in the hill country of Judah and fortresses and towers in the forests.