2 Chronicles 33:14

Rather, “he built the outer wall of the city of David on the west of Gihon-in-the-valley.” The wall intended seems to have been that toward the northeast, which ran from the vicinity of the modern Damascus gate across the valley of Gihon, to the “fish-gate” at the northeast corner of the “city of David.”

We may gather from this verse that, late in his reign, Manasseh revolted from the Assyrians, and made preparations to resist them if they should attack him. Assyria began to decline in power about 647 B.C., and from that time her outlying provinces would naturally begin to fall off. Manasseh reigned until 642 B.C.