They had to survive harsh living conditions.
The Mongols became known as effective and terrible battle strategists. They were like that, because they had to survive harsh living conditions, so they fought to secure their sovereignty. They have perfected their skills over thousands of battles. Even famous historical commanders, such as Alexander the Great and Hannibal, seem far less impressive when their achievements are compared to the smaller of the Mongol generals.
The Mongols relied heavily on shock tactics. Fake encampments, surprise attacks, psychological warfare and even the taking of hostages and the use of human shields were classic Mongolian strategies.
They liked to begin battles by attacking the enemy with a hail of piercing arrows, followed by a brutal charge of cavalry. Often the enemy was attracted to archers hiding behind a weaker mogul force, who apparently seemed to flee.
By attacking large targets, such as large cities, which they could easily encircle two at a time, the Mongols used to advance on extremely wide fronts, using the Yam system to communicate. They were also experts in siege technology and were of a savage brutality towards those who did not submit to their domains.