It may suprise you to know that the Mongols did not go to war at the drop of the hat or for frivlous reason. Genghis Khan sent at least two embassies to the Kwharzemian Shah, and had both of them insulted and/or killed before he was angered enough to crush them. The war between the Timurids and Ottomans was preceded by a series of letters exchanged between Bayezid and Timur exchanging insults, plus the Karaman calling for Timurid help before Timur marched into Anatolia. The Mongols were not simplistic barbarians bent on destruction. They were empire builders and the longevity of their successor states bears testament to that fact.