The area that is now Iraq was densely populated and among the most prosperous and politically important areas in the world continuously for something like four or five thousand years. Under Sumerians, Assyrians, Babylonians, Persians, Parthians, Persians (again), intermittently Romans and Byzantines, and Arab and Turkish Moslems.
Hundreds of wars were fought back and forth across this land over this period. Canals were destroyed, but always rebuilt by the peasantry, reviving the prosperity.
700 years ago the Mongols rolled thru and not only destroyed the canals but killed the peasants. Nobody left to rebuild. The area has never recovered its former prosperity.
Forgot the Greeks in there, though there were also many others over the millenia.