After Genghis Khan decapitated his way through Asia like a mustachioed threshing machine, the Mongolian Empire found direct contact with the Middle East for the first time in their history. As a sign of good will, Genghis sent a caravan into the neighboring Khwarezmid Empire consisting of 450 men and what we can only assume was one damn fine fruit basket.
Like this, but with diamonds and whores.
However, the Khwarezmids did not take kindly to these "people in felt tents," and Governor Inalchuq of Otrar seized the caravan, killing all but one Mongol merchant.
Genghis, at this point, was willing to give his neighbors another chance, figuring that perhaps they simply didn't realize who they were fucking with. He sent a delegation to Inalchuq's boss, Shah Ala ad-Din Muhammad II, to ask what up. The Shah responded by shaving the heads of the Mongol ambassadors, and sent their interpreter home without a head.
Honestly? The guy that got decapitated had it easy.
When he learned about the massacre of his envoy, Genghis nodded and quietly went off into the mountains to count to 10 and compose himself. After thinking it through for a few days, he returned refreshed, then gave Khwarezmid a pounding unlike any the world would see until World War II.
Somehow, this painting fails to capture the carnage.
To avenge his lost messengers, Genghis deployed three of his "four dogs" of war, which included Subutai, better known as the greatest general who ever lived. After laying siege to Inalchuq's citadel for six months with newly-acquired Chinese technologies, Genghis finally obtained a refund for his fruit basket; supposedly by pouring molten silver into Inalchuq's eyes and mouth. Then he went after the Shah.
Genghis Khan stormed into Khwarezmia with up to 200,000 of the best trained soldiers in the world, destroyed an army five times his size, and even diverted rivers to wipe the Sultan's birthplace off the map. By the time Genghis was finished, "not even dogs or cats" were spared. The entire empire was literally erased, its four million inhabitants reduced to mounds of skeletons. The Shah himself escaped to an island in the Caspian Sea, where he died of pleurisy, bankrupt and alone. Thus cementing the popular adage, "don't kill the messenger." Especially if he works for Genghis Khan.