'Middle' in the Bible

(For only Og king of Bashan was left of the remnant of the [the giants known as the] Rephaim. Behold, his bed frame was a bed frame of iron; is it not in Rabbah of the Ammonites? It was nine cubits (12 ft.) long and four cubits (6 ft.) wide, using the cubit of a man [the forearm to the end of the middle finger].)

To the Reubenites and Gadites I gave the territory from Gilead as far as the Valley of Arnon, with the middle of the Valley as a boundary, and as far as the Jabbok River, the boundary of the sons of Ammon;