Why was the invasion of the mongols significant and how did it lead to the advancement of the ottomans and safavids?

The invasion of the Mongols lead to the advancement of the Ottomans and Safavids by bringing with them firepower and arms, which made them superior to all enemies.

The Mongol invasion of Europe in the 13th century was a military effort by the Mongols to invade and conquer Europe. It involved the severe and rampant destruction of East Slavic principalities and major cities, such as Kiev and Vladimir. I hope that this was helpful to you. 

it was on the rise and doing very well and would continue to do well until the great depression from 1929-1939

the deaths of over a million communist soldiers

post-traumatic stress disorder in veterans