A group of Chagatais sent to Baghdad…

A group of Chagatais sent to Baghdad by Timur in 1401 encounter resistance; although more Timurid troops are sent, the city commander, unaware that they are Timur's forces, refuses to give in.

Timur himself soon arrives and Baghdad is subjected to a forty day siege; when it still refuses to surrender, he orders the city stormed in June.

Once it is taken, nearly all of the men, women and children—some twenty thousand of its citizens, including Muslims—are massacred and most of the public buildings are destroyed.

Timur has ordered that every soldier should return with at least two severed human heads to show him (many warriors are so scared they kill prisoners captured earlier in the campaign just to ensure they have heads to present to Timur).

The destruction is so widespread that Timur does not even bother to install a governor.