The Fall of Chaldean

After prospering for a very long time in peace, the once-vigorous Chaldean civilization began to show sign of degeneration. There were few new magical or scientific discoveries, and the people began to idle away and feel complacent. Trades still went on across the empire but the sovereign of the Ashur withered. Later the governors of different regions crowned themselves in their respective territories and only paid nominal allegiance to the far-away emperor.
The ostensible peace continued but no longer mattered as much. Facing twin disasters, the Chaldean civilization lasting for more than two thousand years would all end overnight.
The worst flood in the whole history of Chaldea struck the heartlands of the empire and turned the land into ruins. The rumor went that the death of Eanna, the only deity worshiped by the Chaldeans, caused the flood. What was worse, the Aflar launched a full-scale invasion immediately following the flood. This time the Alfar took their revenge. The defense of the Chaldeans was poor and they lost their rich cities very soon.
However the remote affiliated provinces of the empire sent their help and with the help of the dwarves and Mirdain, they routed the Alfar.
After the war, the city was ruined and the affiliated provinces declared independence. The empire was gone.