Damn! I'd say somebody was pissed! LOL!
Who did that?
Ghengis Khan, after he tried to start a trade empire and the local caliph first imprisoned, then beheaded, his ambassador. The head was then sent back to Ghengis in a sack.
Unfortunately, the murdered emissary was one of Ghengis' best friends. The Khan tore the non-Turkic Muslim world apart to avenge his murder (and who wouldn't???). By the way, it was the 12th century that the Muslims got stuck in (my typo), and most of the bad press we hear about Ghengis entered "Western history" from the viewpoint of the Muslims, from whom European scholars took information on the state of the rest of the world.