Later they realized how much they fucked up.

Genghis Khan once sent a caravan of Mongol merchants to trade with the neighbouring Khwarezmian empire, amid growing tensions between the two. When the caravan reached the city of Otrar, the governor there seized all of the merchandise and put the merchants to death under suspicion that they were spies.

Genghis Khan then sent envoys to the court of Shah Muhammed II to demand the punishment of the governor, but these envoys were humiliated and killed as well. Genghis Khan, considering ambassadors as a sacred role, disengaged from his ongoing war against the Jin dynasty in China and marched his forces towards the Khwarezmian empire, subsequently annexing it into the Mongol empire.