Albert Barnes Commentary Joshua 9:1-2

"And it came to pass, when all the kings that were beyond the Jordan, in the hill-country, and in the lowland, and on all the shore of the great sea in front of Lebanon, the Hittite, and the Amorite, the Canaanite, the Perizzite, the Hivite, and the Jebusite, heard thereof; that they gathered themselves together, to fight with Joshua and with Israel, with one accord." — Joshua 9:1-2 (ASV)

In the hills - See the Numbers 13:17 note.

The valleys - Or “the vale” (the Shephelah, Deuteronomy 1:7), which refers to the lowland country between the mountains and the sea coast.