Mongol forces under Hulagu Khan completed the sack of Baghdad, ending the Abbasid Caliphate after nearly 500 years of rule.

In the aftermath of the Mongol siege, Baghdad's canals ran black with ink from destroyed libraries as the Abbasid Caliphate's intellectual capital lay in ruins.

In the aftermath of the Mongol conquest, survivors in Baghdad continued burying the dead as the Tigris ran black with ink from destroyed libraries.